She sleeps nine hours.为什么nine前不要加for?

She sleeps nine hours.为什么nine前不要加for? She usually sleeps (nine hours) a day对括号内提问 （）（）does she usually sleep a day sleeps for nine hours 的同义句 sleeps for nine hours同义句 My brother often sleeps f____ nine hours a night. He sleeps for nine hours over night的问句 She often goes to ( )at nine,but now she is ( )括号里填什么?如题,A:sleeps ,sleepingB:sleep,sleepingC:sleep,sleepD:sleeping,sleeping请各位帮忙看看是哪个选项,感激不尽! He sleeps nine hours every day.[对nine hours划线提问] kate sleeps nine hours every night中对nine hours提问 She is a lazy girl,she sleeps _______(always) my little brother sleeps (nine houes) every day.对括号提问 Dacid usually sleeps for nine hours every day 同义句在等 Danid usually sleeps for nine hours every night 改为同义句? David usually sleeps for nine hours every night.改为同义句怎么改?急 5.Students ______ nine hours a day.A.sleeps B.sleep C.are sleep She sleeps (seven) hours every day 对划线部分提问 she worked at night but sleeps in the d_________ she sleeps at nice hours every night 改错