用在每个语境中,有什么标志词?
以have 为例,首先第三人称单数形式has,用于一般现在时,标志词usually ,often ,never ,once a week ...having 是其分词形式,用于现在进行时和过去进行时。比如 I am having lunch now . I was having lunch when you called me. 标志词now,these days... at this time yesterday ....过去式had,用于过去时。例如She watched TV for two hours last night.标志词都很多,主要是过去的时间点,yesterday,last year,two days, ago....to do不定式是另一种形式,用法很多,可在句子中做主语,宾语,表语,宾语不足语,定语,目的状语,虽然多,但是比较好理解,可以百度一下。另一个是过去分词had,用于现在完成时和过去完成时,例如 I have already had lunch at school.标志词较多,so far ,already ,before,just,since ...
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