______ does he go to Guangzhou on business —Three or four times a year.

下列各选项中，没有语病的一项是（ ）

(2013·陕西，18)I have heard a lot of good things about you ________ I came back from abroad.

Laura didn’t join in theirdancing last night , did she —________________,because she fell off her bike and hurt her legs

When you do exercises, your heart works better. It is able to______ more blood while beating more slowly.