I soon found that the work I was doing had already been done by someone else. _______, I was wasting my time.

 Many friends sent me e-mail to ________ me on the birth of my son.

 Many people ________ the accident, so it was not difficult to investigate（调查）.

It was along the Mississippi River _________ Mark Twain spent much of his childhood.

 In 1938, Hitler _________ war against Poland, which started the Second World War.

A serious earthquake struck the village, __________ many people homeless.

The old woman _____ her sons and daughters _______ and see her soon.

The pretty girl is always busy helping her mother with the housework _________ I go to visit her family.

______ more effectively in the future, many people equip themselves with further education.

We often go to ________ school library because we can have such easy access ________ the Internet there.