I/ Rewrite the sentences in the impersonal form of the passive :

1. The tourist have said that the best time to visit Son Doong Cave was in March

3. Scientists have discovered that there is water on Mars

4. They know that English is an international language

II/ Rewrite the sentences, using question words + to inf: 

1. They can decided what they should do in this situation.

2. I don't know where I should go on the weekend

3. She was not sure where she put her mobile phone. 

`1)` It has been said by the tourists that the best time to visit Son Doong Cave was in March.

`2)` It has been discovered by scientists that there is water on Mars.

`3)` It is known that English is an international language.

`->` It + be + V + (+by O) + (that) + ...

`->` be ở đây là is/has/had

`-`

`1)` They can't decide what to do in this situation.

`2)` I don't know where to go on the weekend.

`3)` She was not sure where to put her mobile phone.

`->` can(not) + V-inf: có/không thể làm gì

`->` do/does (not) + V-inf: (không) làm gì

`->` wh- + to + V-inf

`-`

@magnetic