Помогите не решить,а подскажите какие здесь правила нужно для экзамена выучить,подобные вопросы будут
1.
I asked my brother if he ... me.
1) will help 2) helps 3) would help 4) would have helped
2.
I wonder when she ... my books.
1) returns 2) would return 3) will return 4) had returned
3.
You'd better ... this dress. It's too small for you.
1) don't buy 2) didn't buy 3) not to buy 4) not buy
4.
There’s something wrong with my washing machine. I must...
1) repaired it 2) to repair it 3) have it repaired 4) have it repairing

Во-первых ,всё неправильно у меня есть ответы,а во-вторых,я попросил правила по которым делать эти задания

1.-I asked my brother , if he helps me.2.-I wonder when she will return my books.2.-You`d better don`t buy this dress.It`s too small for you.4.-There`s something wrong with my washing mashine.I must repair it (to repair)