该公司声称（它）对河流污染不负责任。

The company ___claims ___that it is not responsible for pollution of the river.

他声称见过总统，但我不相信他。

He ___claims to have met the President, but I don't believe him.

一个未知的恐怖组织声称对今天早上的炸弹袭击负责。

An unknown terrorist group has ___claimed responsibility for this morning's bomb attack.