The ______ of air and water makes it impossible to live on the moon.

In many cultures people who were thought to have the ability to ________ dreams were likely  to  be highly respected.  

The moment I completed the 3000-meter race in the school sports meet, my legs _______．

I have no ________ to the plan, so long as it would not cost too much.

(2013·济南市一模)—I will have to think about it again.—If you ________， you may lose the opportunity to compete altogether.