It is ______ that the noise around us is a(n) _______ to our health and well being.
| A．preventable; precaution | B．denial; existence |
| C．undeniable; hazard | D．vital; culprit |
Samples of blood from Cholera infected patients have been sent to the blood center _______.
| A．to be checked | B．to be examined | C．to test | D．being tested |
After several years of observation, the research group ______ the conclusion that language acquisition is faster when students ______ to the situation where it is spoken.
| A．has come to; expose | B．have arrived at; are exposed |
| C．has concluded; are exposed | D．have reached; expose |
It will be many years ______the doctors and medical scientists can find _____ for cancer.
| A．since; cures | B．when; treatments | C．before; cures | D．until; treatments |
We have to ______ everything question in detail ______ we take action.
It is clear that no use can be made ______radium _____we don’t know clearly the characteristics of it.
| A．from; if | B．of; unless | C．from; unless | D．of; if |