6. Mary didn't wear the raincoat, so she got a cold.

→If

7. I couldn't do the test because it was too difficult.

→ If

`-` Chuyển sang câu điều kiện loại `3`: Diễn tả `1` điều kiện không có thật ở quá khứ.

`-` Cấu trúc: If + S + had + P2, S + would /could + have + P2

`->` Bạn tham khảo :

`6`, If Mary had worn the rain coat, she couldn't have gotten a cold.

`7`, If the test hadn't been too difficult,I would have done it.