—Why did you talk to the teacher after class? —I don't understand ________ during the lecture.
| A．the problem did she tell us | B．how did she say |
| C．that she was talking about | D．what she was teaching |
Edison had built a chemical lab of ___ when he was very young.
| A．himself | B．him | C．itself | D．his own |
This is the only one of the books on space ___.
| A．that has been written | B．that have been written | C．which have been written | D．which has been written |
---Please help me, will you? ---_____.
| A．You’re welcome | B．Of course, I will | C．Not at all | D．It’s my pleasure |
The twins looked exactly the same.Even I couldn't ___ one from the other.
| A．speak | B．talk | C．say | D．tell |
Beijing is ___ capital of Chian, ___ everybody knows.
| A．the, as | B．a. which | C．/, like | D．the, which |