Stress can be extremely damaging to your health. Exercise, _, can reduce its effects.

He had ever climbed this mountain several months before, but ________ he couldn’t find the way this time.

Since Tom_____ downloaded a virus into his computer, he can not open the file now.

The opening ceremony of the 29th Beijing Olympic Games was _____ that everybody was greatly impressed_____ it.

Most of the evidence was destroyed in the fire. ______, it would be almost impossible to prove Jim guilty.