for a long time he has been __ the causes of sleepA checking B investigating C proving D revealing

He sat there for a long time w___ doing anything He ____ me _____ for a long time yesterday. .He sitted there for a long time without doing anything. He has been __(wake) for a long time 2.He _____ the city for a long time.2.He _____ (leace)the city for a long time. He stayed there for quite a long time ,bring [ ] time he learned much spoken English. he lost his job a long time ago同义句he has ------ ------ ----- work for a long time Fortunately,he passed the English exam a---------- he had been ill for a long time. he asked he asked the farmers to work for a long time改为被动语态 he always f() tried after he runs for a long time 请问He has been waiting for his brother for a long time.是什么时态,语法 翻译：He has been waiting for his brother for a long time. we work for a long time.for? He sitted there for a long time without doing anything.哪错了`a for a long time he had expected to get a beautiful sports car.的意思. he has been worried for a long time since he____(ask)to give a talk 是不是只有for a long time,没有for long time和for long times? for long与for a long time的区别