【正文】
含有since時間短語的句子要用完成時,但含有for時間短語的句子不一定要用完成時?! ∪纾篠tay over the Christmas. (5) for與since:for表示動作或狀態(tài)延續(xù)的全部時間長度,為“長達……”之意。如:on Saturday, on Saturday morning, on the morning of August 1st (3) at表示“在某一時間點”,或用來表示不確定的時間和短期的假日、時節(jié)等。in也可以指“在……之后”,表示從說話起的若干時間內(nèi)?! ∪? now, today, this month, this year, recently, these days,many times, so far, by now, in the past/last few days/years… 等?! ±篘ot all the students have been to the Austrlia. She can’t work out both of the difficult problems. Everybody cannot work out the problem. Neither,none 和含有 no 的復合代詞表示全部否定。each of them has go