1.People believed that he was mad. 2.People believed that he is mad. 3..People've believed that he is mad.

`Đáp` `án:`

1. 

- It was believed that he was mad.

- He was believed to be mad.

2.

- It was believed that he is mad.

- He was believed to have been mad.

3.

- It has been believed that he is mad.

- He has been believed to be mad.

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Câu gốc: S1 + V1 + that + S2 + V2 

→ S2 + be + V3/ed (V1) + to + V1 

→ S2 + be + V3/ed (V1) + to have + V3/ed 

→ It is + V3/ed (V1) + that + S2 +V2