2 과거완료는 반드시 같은 문장 내에 과거의 기준 시점(과거 시제 등)이 존재해야 한다.

주의 해야 할 사항들

1. before와 after가 있는 경우는 과거 완료를 쓸 자리에 과거를 써도 된다.

Before I made a decision, I had thought carefully about it. (O)

Before I made a decision, I thought carefully about it. (O)

I made a decision after I had thought carefully about it. (O)

I made a decision after I had thought carefully about it. (O)

2 and나 but으로 문장이 연결된 경우는 사건이 먼저 발생했다고 해서 과거 완료를 쓰지 못한다. 둘 다 과거를 쓴다.

Yesterday we had sailed eastward over a smooth sea and at sunset almost reached Algiers. (X)

è Yesterday we sailed eastward over a smooth sea and at sunset almost reached Algiers. (X)

He passed his driving test first time, which surprised me.

=He passed his driving test first time and it surprised me.

3. 동시 상황 혹은 즉시 상황인 경우, 양쪽 모두 과거를 사용한다. (두 사건 사이에 시간의 간격이 없다)

When she saw a snake, she screamed.

I was shocked when I opened the box.

As soon as she saw me, she started crying.

When I fixed the hard drive, my computer became faster.