The maths problem remained confusing to the boy although _______ over and over.
| A．explaining | B．being explained |
| C．explained | D．having explained |
It is known to all that every minute ____ full use of____ the lessons will benefit students a great deal．
| A．which makes; studying | B．when made; to study |
| C．that made; to study | D．which is made; studying |
It really seemed ages ____ the police came on the scene and cleared away the damaged cars．
| A．before | B．after | C．when | D．as |
—I'm sorry, but there's no smoking room in this section on the train．
—Oh, I ____that, and I won't smoke again．
| A．don't know | B．won't know | C．didn't know | D．haven't known |
____ new round of competition for customers has started with discounted products in Gome and Suning, setting off____ wave of shopping rush at the end of the year．
| A．A;不填 | B．The; a | C．A; the | D．A; a |
—It has been a wonderful evening．Thank you very much．
— .
| A．I’m glad to hear that | B．My pleasure |
| C．No, thanks | D．Don’t say so |