The book is meant to ___needs it .
We _________ some money every month in order to buy a computer.
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.