下列各句中，加横线的成语使用正确的一项是（ ）

I’ve finally finished my research paper.—______________. It must have been a hard job.

Do you have any plans for this summer vacation–I’m not sure. I ___ take a trip to Taiwan.

We have many eggs in the fridge. You ________ buy any more.

Nobody wanted to ________ matters for him though everyone knew that he was blameless.[ ]