Our bodies are strengthened by taking exercise．_______ our minds are developed by learning．

I can’t finish this job by Friday. You expect too much of me.

——It will be terrible to see the nuclear war happen. ——That’s right. Nuclear science should be developed to benefit the people   _____   harm them.

Don’t blame them any more---this is _____ because they are still young and lack experience.

 With more and more farmers moving to cities, an inadequate labor force is    becoming a major factor affecting the country's grain output.