What grammar structures are required to be used in the Russian A2 level examination?

One of them is a conditional structure with "если бы".

The general rule is: "Если бы" indicates that the action has not taken place and so the result differs from the one we expected. Verbs in such constructions are usually used in the Past Tense. An example: Если бы она пришла сегодня вечером, то мы бы поговорили об этом [If she had come today in the evening, we would have talked about that], implying that in the real life, she did not come and the situation did not take place.

"Если бы" can also be used to state a request. For instance, Если бы ты слушала меня, всё было бы хорошо [literal translation: If you had listened to me, everything would have been fine], however, can also mean a request: Listen to me in the future and everything will be fine!