`18`. The sea animals are believed to have died due to water pollution.

hoặc: It is believed that the sea animals have died due to water pollution.

`19`. She is thought to be in South Korea.

hoặc: It is thought that she is in South Korea.

`20`. He is said to be hiding in the countryside.

hoặc: It is said that he is hiding in the countryside.

`21`. The suspect is known to be dealing with unreal money.

hoặc: It is known that the suspect is dealing with unreal money.

`-` Câu bị động "kép": It+ is+ V2/ Ved+ that+ SVO

`≈` S2+ is/ am/ are+ V2/ Ved+ to V

`18.` The sea animals are believed to have died due to water pollution.

It is believed that the sea animals have died due to water pollution.

`19.` She is thought to be in South Korea.

It is thought that she is in South Korea.

`20.` He is said to be hiding in the countryside.

It is said that he is hiding in the countryside.

`21.` The suspect is known to be dealing with unreal money.

It is known that the suspect is dealing with unreal money.

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Câu bị động dạng đặc biệt với động từ chỉ ý kiến (say, think, believed, report, rumour, know,...):

S+V+(that)+mệnh đề (S2+V)

`->` It+tobe+V3/Ved+(that)+mệnh đề (S2+V)

`->` S2+tobe+V3/Ved+to Vinf/to have V3/Ved/to be V_ing+...