Listening to loud music at rock concerts _____ caused hearing loss in some teenagers.
| A．is | B．are | C．has | D．have |
The children all turned ______ the famous actress as she entered the classroom.
| A．looked at | B．to look at |
| C．to looking at | D．look at |
Edward, you play so well. But I ______ you played the piano.
| A．didn't know | B．hadn't known |
| C．don't know | D．haven't known |
She brought with her three friends, none of ______ I had ever met before.
| A．them | B．who |
| C．whom | D．these |
I tried phoning her office, but I couldn't ______ .
| A．get along | B．get on |
| C．get to | D．get through |
His sister left home in 1998, and ______ since.
| A．had not been heard of | B．has not been heard of |
| C．had not heard of | D．has not heard of |