he skated for four hours 为什么加for

he skated for four hours 为什么加for San skated for four hours 对划线部分提问 I skated for four hours与I have been skating for four hours的区 -How long did you skate?-I skated for two hours. my brother skated for the w___two hours yesterday i've been skating for five hours=i skated for five hours I skated for 4 hours . I have been skating for 4 hours. I ha By 11 o’clock,he will ____ for four hours. he`s been skating for four hours 改为否定句 He can get up for two hours each day.这句话为什么要加for .直接说He can he is p____ enough to wait for me for about four hours. He'd better ___ (not eat)anything for twenty four hours.