his hobby is collecting car posters 同义句转换 适当形式填空 The coat is （grandpa）Please stand behind （boy）It‘s cold .（do)take off your sweaterHow many （baby）are there in the zoo there are my bags please look after （they）for me

同义句：He is fond of collecting car posters.原句意思是他的爱好是收集汽车海报，所以改成他喜欢收集汽车海报这种类型的句子应该都是可以的。
填空：The coat is grandpa's.本句是说外套是爷爷的，所以是所有关系。
Please stand behind the boy.该句意思是请站在那个男孩后面，因为是特指某个男孩，所以加定冠词。
It's cold. Don't take off your sweater.前一句意思是天冷了，所以后面的用不要脱掉毛衣。

he enjoys collecting car posters.
the coat is grandpa's.

His hobby is collecting car posters.同义句：He likes collecting car posters.
适当形式填空：The coat is grandpa's .
Please stand behind the boy.
It's cold.Don't take off your sweater

He collects car posters as his hobby.
grandpa`s
the boy
Don`t