4. 现在完成进行时(have been doing) 用法:表示某一动作开始于过去某一时间,延续或重复地出现至今,或将继续延续至将来。 例:We have been working on this project for over a month now.(到目前为止,我们一直在处理那个项目,已经花了一个多月时间了。) 注意事项:与现...
【起止标识】标记非谓语动词短语时,一定是从动词不定式(to do)、动名词(doing)或分词(现在分词doing或过去分词done)开头,到以下四种情况终止。 ① 到句尾终止,如:Li Hui is a teacher (teaching English). ② 到句中的逗号终止,如:(To improve my English), I often l...
2、They have done things they ought ___ A. not to do B. not to be done C. not to have done D. not having done 3、I' m sorry I couldn't get in touch with him before he left, I ___ him earlier. A. had a telephone B. have phoned C. should have...
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