问题

It is pretty well understood ________ controls the flow of carbon dioxide in and out the atmosphere today.

A:that
B:when
C:what
D:how

正确答案是：

同类题型

The seals were stranded（搁浅）on the Rhode Islandbeaches,_____ they were rescued last year.

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he come to see you today —- Of course,please And I’drather she _____ me the truth

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