变否定句的方法及习题：一、 句中有Be(am,is,are,was,were)动词的时候，直接在Be(am,is,are,was, were)动词后加not, 通常缩写。Lg. 1.Im a cook. -Im not a cook.2.Tom is watching TV. -Tom isnt watching TV.3. They were students in a school 10 years ago.-They werent students in a school 10years ago.4. She is going to study computer science. -She isnt going to study computer science. 2、 句中有情态动词时候，在情态动词（can, may, must, might, will, would, should）后加 not, 通常缩写。Lg.1.I will go to Shanghai next year.-
