Ét ô ét giải giúp em với ạ

A.

1. The father took off his mask so that his children would not be frightened.

2. Not until the boy’s father threatened to punish him did he tell the truth.

3. If we hadn’t been busy last night, we would have gone to the concert.

4. (Mình không hiểu yêu cầu đề bài lắm, có gì bạn giải thích sau nha)

B.

1. Not until 1980 did she begin to learn English.

2. (Giống câu 4A)

3. Paul locked the door of his room so that his children could not disturb him.

4. If Peter hadn’t prepared his lessons well, he could not have got good marks.

Vì lâu rồi mình chưa làm những dạng bài này nên có thể có sai sót, bạn tham khảo thôi nhé!