Do you know the most ancient city in China—Xi’an well—No, this is the first time I ________ here.

Have you found the information about Bill Gates________ you can use for the report —Not yet. I’ll search some on the Internet.

sterday it was too late to get back,so Iat my aunt’s

How did you _________ the company— It used to be _________ my father. He gave it to me after his retirement.

________ these experiments were successfully completed would we think of going into humans.