Question 14: How can I use "как будто" in a sentence?

The expression "как будто" is usually translated as "as if" or "like". Let's have a look at some examples:

1. Он смотрит на тебя странно, как будто он хочет что-то спросить. = He is looking weird at you, as if he wanted to ask you something. (in Russian, there is no need to use the past tense after "как будто" in the meaning of "as if")
2. Ты как будто болеешь. Что с тобой. = You look like you are ill. What's wrong with you?
3. Конечно, я хотела пойти на этот концерт! Как будто ты не знал! = Of course, I wanted to go to this concert! Like you didn't know!

Question 13: How can I say in Russian "It's nice". Should I use "Оно хорошее?"

When we use general expressions about no object in particular we use adverbs. For example:

Здесь хорошо и уютно. = It's nice and cosy here.
Ты здесь! Замечательно! = You are here! Great!

We use "оно" when referring to a neuter noun:

Это твоё новое хобби? Оно хорошее. = Is this your new hobby? It's nice.
Мне нравится твоё платье. Оно красивое. = I like your new dress. It's cute.

Question 12: My Russian friend say that "У меня есть зелёные глаза" sounds funny. Why? Is it a mistake?

If you forget to omit "есть" when speaking about someone's appearance you might sound a bit funny for a Russian ear. Since "есть" expresses possession it sounds like you are saying "I have some green eyes" (as if you had a collection of different eyes).

You should also be careful while expressing negation in these situations. You just have to put "не" before the word you negate. Don't use "нет":
У него не короткие волосы, а длинные. = His hair is not short, but long.
У них не зелёные глаза, а голубые. = Their eyes are not green, but blue.

If you use "нет" you will negate the fact of having something whatsoever. For example:
У него нет волос. = He doesn't have any hair.
У монстра нет глаз. = The monster doesn't have eyes.

Question 11: When should I omit "есть" in Russian? Do "У меня есть" and "У меня" mean the same?

You probably know that in Russian we use the construction "У меня есть + the nominative case" to express possession ("I have..."). However, there are sentences where "есть" is omitted. It happens when instead of expressing possession, we give a characteristic of something, for example:

У меня хороший характер. = My character is good. (You can also translate it as "I have a good character". What matters here is the quality of the thing, not the fact of having it. In the end, everybody has a character but not everybody has a good character.)
У неё короткие волосы. = She has short hair.
У тебя длинный отпуск? = Is your vacation long?

Attention! We often omit "есть" when we describe people's appearance. The most common mistakes among Russian students are the following:
У меня зелёные глаза. (not "У меня есть...") = I have green eyes.
У неё длинные волосы. (not "У неё есть...") = She has long hair.
У него большие уши. (not "У него есть...") = He has big ears.

Question 10: How to say "I don't have" in Russian?

To say "I don't have" we use "У меня нет...". But be careful! After "у" and after "нет" we have to use the genitive case:
У меня нет кошки. = I don't have a cat (literally we say "In my possession, there is no cat")
У тебя нет братьев? = Don't you have any brothers? (literally "In your possession, are there no brothers?)
У него нет дома в деревне. = He doesn't have a house in the countryside (literally "In his possession, there is no house in the countryside).

Question 9: How to say "I have" in Russian?

Saying "I have" in Russian is a little tricky because we don't use the verb "to have" in this meaning. Instead of this verb, we use the construction "У меня есть..." which literally means "In my possession there is..." Let's have a look at some examples:
У меня есть кошка. = I have a cat (literally we say "In my possession, there is a cat").
У тебя есть братья? = Do you have any brothers? (literally "In your possession, are there any brothers?)
У него есть дом в деревне. = He has a house in the countryside (literally "In his possession, there is a house in the countryside).

As you might have noticed, after the preposition "У" we have to use the genitive case (у меня / у тебя / у него / у неё / у нас / у вас / у них). The thing that we possess is used in the nominative case because it's the subject of the sentence.

Question 8: How to say "I love it!" or "I loved it" in Russian?

In Russian, only the verb "нравиться" should be used in this meaning (not "любить"). Have a look at the examples:

Какое у тебя красивое платье! Мне очень нравится! = What a beautiful dress you have! I love it!
Вчера мы ходили в театр. Мне очень понравилось! = Yesterday we went to the theatre. I loved it! The verb "понравиться" is a perfective couple of the verb "нравиться" it means that you liked something (a finished action in the past)

Question 7: What’s the difference between “если” and “ли”? Do they both mean “if”?

It's very easy to mix up the words "ли" and "если" when you learn Russian because both words can be translated into English as "if". In Russian they are quite different from each other. Let's see how to use them correctly.
We use "если" to express a condition:
Если завтра будет дождь, я буду дома. = If it rains tomorrow I'll stay at home. Pay attention that in Russian, we have to use future in both parts of the sentence (будет дождь, я буду дома).
Ты можешь взять мой велосипед, если хочешь. = You can take my bike if you want.

We use "ли" to express a doubt about something. You can also translate it as "whether". In fact, try to associate "ли" with "whether" in your mind and you won't mix it up with "если" any more:
Я не знаю, будет ли завтра дождь. = I don't know whether tomorrow it's going to rain.
Я спросил его, хочет ли он взять мой велосипед. = I asked him whether he wanted to take my bike.

Where should I put "ли" in a sentence? We usually put "ли" after the word that expresses the actual doubt. Compare these sentences:
Я не знаю, купил ли он хлеб. = I don't know whether he bought bread.
Я не знаю, хлеб ли он купил. = I don't know whether it was bread that he bought (or something else).
Я не знаю, он ли купил хлеб. = I don't know whether it was him who bought the bread.

As you must have noticed the "doubt" always comes first in the subordinate clause. If you change the word order you will also change the focus of the doubt.

Question 6: What case is used after "любить" and "нравиться"?

The verb "любить" requires a direct object in the accusative case. The verb "нравиться" uses a different structure and the dative case. Let's have a look:
Я люблю вкусную еду. = I love/like delicious food. The words "вкусную еду" are in the accusative case.
Мне нравится вкусная еда. = (literally) Delicious food pleases me. The words "вкусная еда" are in the nominative case because they are the subject of the sentence. Who pleases me? The food does. The word "мне" is in the dative case.

Я люблю мою кошку. = I love my cat.
Мне нравится моя кошка. = (literally) My cat pleases me.

Question 5: Is Russian word order really flexible or are there rules?

Russian word order seems to be flexible but it follows a very important rule: the "new" information usually stands at the end of the sentence. So, any word order is grammatically correct but the meaning of the sentences will be slightly different. For example:
Я часто хожу в магазин. = I often go to the shop. This word order is neutral.

If you change the neutral word order you’d probably put more importance on the word at the end or mark it as a new one. Read these sentences out loud to stress the last word:
Часто я хожу в магазин. = Often, I go to the shop. (Where do I go?)
Я хожу в магазин часто. = I go to the shop often. (How often do I go to the shop?)
Часто в магазин хожу я. = The one who often goes to the shop is me. (Who goes to the shop?)

That's basically how Russian word order works. The neutral word order is quite simple (Subject + Predicate + Object). Once you start changing it, you also slightly change the meaning of the sentence. However, the intonation is also important.

Question 4: What is the difference between "привет" and "здравствуй(те)"?

"Привет" is used only in informal situations normally with your friends or close people. It is never used in semi formal or formal situations., i.e. we can use “привет” in very limited situations.
"Здравствуйте" is formal and is used in plenty of situations (addressed to 1 person or many people): almost always to people you don't know well or in any formal situation or at least slightly formal (neighbours, salespersons, teachers, passers-by etc.)
"Здравствуй" is addressed to 1 person, and it is really strange as it it neither formal, nor informal, it is rarely used and really specific, e.g. it could be used when addressing a child in a semiformal way or 1 person you used to know well, but haven't seen for a long time, etc.

Question 3: What’s the difference between the conjunctions “и” and “а” in Russian? Do they both mean “and”?

Usually, the connectors “a” and “и” are both translated as “and” in English. But their meanings are slightly different.
We use "a" in the following situations:
1. There is some kind of contradiction or contrast between the previous sentence and the next one (or between clauses in a complex sentence):
Я люблю кофе. А мои друзья любят чай. = I like coffee. And my friends like tea.
Я люблю кофе, а не чай. = I like coffee and not (=but not) tea.
2. You make a question like "And you?"
Я люблю чай. А ты? = I like tea. And you?
Меня зовут Анна. А вас? = My name is Anna. And yours?

We use "и":
1. to connect two words in one sentence (typical meaning of "and"): Я люблю чай и кофе. = I like tea and coffee.
2. to connect two clauses that have the meaning of "I do it and they do it too": Я люблю кофе, и мои друзья любят кофе (in the meaning of "тоже"). = I like coffee and my friends like coffee too.

Question 2: Should I say "Тебе всё хорошо" or "У тебя всё хорошо"?

To ask "How are you?" the second option is correct. Using "тебе" is also possible but with a different meaning:
Я надеюсь, что тебе хорошо. = I hope you are feeling ok.
Я надеюсь, что у тебя всё хорошо. = I hope things are ok with you.

Question 1: Should I say "Сколько картин висело or "висели" на стене?"

In Russian, we usually use the verb in the neuter singular form after "сколько"
Сколько картин висело на стене? = How many paintings were hanging on the wall?
Сколько людей работало на фабрике? = How many people were working at the factory?
With animate nouns, plural is also possible but not as frequesnt as singular: Сколько людей работали на фабрике?