这个句子为何不用过去完成时?The anti-virus agent was not known until a doctor found it by chance.我觉得应该是The anti-virus agent was not known until a doctor had found it by chance.因为我觉得“医生发现”这个动作在

Father asked Anne when she went to bed the night before.这个句子中可以不用换为过去完成时吗? 这个句子为何不用过去完成时?The anti-virus agent was not known until a doctor found it by chance.我觉得应该是The anti-virus agent was not known until a doctor had found it by chance.因为我觉得“医生发现”这个动作在 It seemed as if the world was at an end!为什么不用过去完成时 That is what I have been expecting since my childhood.为何不用过去完成时? he pretended to have read the book before 有三个问号哦这句子是现在完成时吗?若是,那请问为什么用现在完成时,而不用过去完成时呢?用了过去完成时意义是什么? after he was arrested,the man …after he was arrested ,the man admitted hiding in the box before the plane left London.1.he was arrested为什么不用过去完成时?2.动名词hiding做动词admit的宾语这个规则在任何句子中都通用吗 英语关于since用法的一个问题!有一个句子是：Since the government was bankrupt,many of the soldiers who were sent to quell the riots had not been paid in months.为什么要用“had been”这个过去完成时而不用现在完成时 Take English as an example,the foreign language...这句话中为何不用Taken 或To take开头?是什么用法?如果是祈使句 那两个句子怎么能用逗号连接？ 帮我分析一句英语句子吧The blunder made the underground instrument undergo an undermining of the thunderbolt.这个句子的谓语是made吧?还是undergo?用了made是过去式,但是undergo为什么不用? the students all stood up when the teacher.进入 The classroom为什么enter不用过去完成时, 过去完成时与一般过去时的问题今天晚托班的时候遇到个初三学生，他们英语这个单元学的过去完成时，然后有两句句子中译英大致如下：1.Lily ran back to the school because she had left her homework in when 引导的时间状语从句用一般过去时,主句用过去进行时或者过去完成时.那么he was walking along the road when it began to rain 这个句子中主句有过去进行时或者过去完成时吗? 英语 过去完成时 untilI did not understand the problem until he had explained it.过去完成时表示两个动作中较早的过去.这个句子中,明明是先不懂、再解释,为什么had放在解释那边? On arriving at the shore ,the girl struggled up the cliff towards the light she had seen.这句子后面的宾语从句为什么要用过去完成时had seen而不用一般过去时saw? This it is an eraser.这个句子该用在哪,怎么用?为什么不用This ls an eraser. 初三过去完成时句子 how long did you skate?I skated for two years.是持续的时间为何不用过去完成时. A few years after he __(became) ruler,his wife ,Mumtaz-i-Mahal,died 为何不用过去完成时