Smoking has a strong harmful ________ on our health.

The United Nations has, on numerous occasions, tried to assert its authority to mediate a dispute between nations, --------- has often been ineffective --------- the nations involved refused to acknowledge the right of the United Nations to intervene.

This is not a new theory; quite a lot of scientists ------- on it for several decades.

If the equipment ------- us on time, we ------- the bridge by now.

Unfortunately there was an electricity cut just as we ------- the new computer.

It is recommended that you wear a helmet in this part of the plant, but it's up to you; you -------.

-------- a piece of metal is denser than water, it sinks in water.

-------- he was aware of the dangers of this kind of research, he still continued with the project.

------- the semester is over, Dr. Baines will supervise the sinking of the shaft as it seems likely that they'll strike oil.

It took him several months to set ------- the experiment, but results are beginning to come ------- now.

Obviously, during the Second World War, many scientists were involved ------- the development of new weapons.

He filled the glass with water to the _______ .

It is no use ______ to come now. He is very busy.

The police _________ the thief yet.

He always avoids ______ to strangers.

He was frightened __________ .