________ the suggestions will help to achieve your goal of a job in the medical profession.

下列各句中．没有语病的一句是（ ）

Scientists are convinced ___________the positive effect of laughter_________ physical andmental health.[ ]

I don’t think your children could have been used to the quick pace of life while working in Shenzhen, _____they?—_____. They thought of returning to Changchun.

Do you know where David is He is not in the office.–Well, he ______ have gone far—his coat is still here.