I think English is __________ unimportant subject.— I don’t think so. It is __________ useful tool when we talk with foreigners.

下列各句中，没有语病、句意明确的一项是（ ）

He ________ stay at home and look after his mother yesterday.

Twenty-five people died in the traffic accident in Guizhou Province. It’s _______ one that I have ever heard of.

My request is that the information referred to in my report ________ Mr. Brown without delay.