状语从句省略不是涉及该用动词的ed形式还是ing形式或have +动词ed.这样的用法如何判断,

1.如果是被动语态，状语从句省略时，主要动词用ed 的形式。When an animal is shot, it connot run away.省略后为：When shot, an animal connot ryn away.
2. 如果是主动语态，分两种情况：
（1）各种完成时，状语从句省略时，助动词have(has,had)用having 的形式,并保留动词过去分词形式不变。After he had read, he slept.省略后为：After having read, he slept.
（2）其它时态，状语从句省略时，主要动词用ing的形式。When he aet(or eats or is eating or was eating), he made noises.省略后均为：When eating, he made noises.

状语从句的省略：当状语从句的主语和主句的主语一致，并且从句的谓语是be动词时，就省掉从句中的主语和be动词。大多数情况就和分词短语做状语一样了，有时候也会是形容词做状语，表状态。
e.g。1.When you are crossing the road,be careful (状语从句）
=（When)crossing the road,be carefull.
2.(If water is )heated,it can turn into gas..
3.Although ( he was )tied,he kept on reading.
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状语从句省略不是涉及该用动词的ed形式还是ing形式或have +动词ed.这样的用法如何判断,高手帮忙.0分
答：状语从句省略"主+Be"条件是其主语与主句的相同或为it谓语中有be动词如When (water is) heated, water will become vapour.
When (you are )crossing the street, you should be careful.
If (it is) necessary, I will help you.
没有第三情况.

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