Dr. Frank failed many times but he finally ______ to find a successful way to solve the problem.
| A．broke off | B．broke up | C．broke down | D．broke through |
.Danny left word with my secretar
yhe would call again in the afternoon.
| A．that | B．who | C．as | D．which |
Thelook on his face showed that he was greatlyof being left alone in the house.
| A．terrified;terrifying | B．terrified;terrified |
| C．terrifying; terrifying | D．terrifying; terrified |
Having a large family to support, Mr.Johnson had to workin the evening.
| A．four another hours. | B．more four hours. |
| C．other four hours. | D．four extra hours. |
—When did you get to know the professor over there?
—It was at the work shopwe did reserch to gether two years ago.
| A．that | B．there | C．which | D．where |
I have read a series of stories about some world famous great scientists,are from our country.
| A．two of them | B．two of whom | C．both of them | D．both of whom |