After running for such _____ long time, everyone was out of _____ breath.
| A．不填; 不填 | B．不填; the | C．a; the | D．a; 不填 |
_____from lightweight materials，the robots are about the size of a human arm or
smaller．
| A．To build | B．Being built | C．Having built | D．Built |
The fact that smoking is harmful to health is____most smokers are quite aware of．
| A．what | B．which | C．where | D．that |
An example of them is fraud, a crime _______ money is stolen by cheating others.
| A．which | B．that | C．what | D．where |
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 |
---Where have you been?
---I got caught in traffic, otherwise I _______ here earlier.
| A．would be | B．have been | C．had been | D．would have been |