问题

________ many times，I stilldidn’t know how to operate the machine.

A:Having taught
B:Having beentaught
C:Being taught
D:Teaching

正确答案是：

同类题型

s article , you need to back up general statements with ________ examples.

She picked up a wallet _____ home.[ ]

Is Mike your brother—______. He’s my friend.

. — Do you play computer games — Yes. They’re very __________.

e opened the box, it ____________ a bad smell