We should make a careful study of his____.

.---How long did Mary work here?---For half a year, but she didn’t leave us much ____. We hardly remember what she is like. 

I bought a vase of the Ming dynasty at such a low price at the Sunday market. It was really a nice __________.

_______, when I went to town to see my sick teacher, he said to me, “I’ll come back to school again _______.”

Few people back then had cell phones,and almost no one had____to the Internet.