第1个回答 2022-01-23
不加。加了sb.之后before所引导的是一个从句,故是一个完整的句子,因此不用现在分词,若不加sb.也before引导的是一个状物,故要用doing.综上所述,if you add "sb.",you'll be unable to use form "doing".That's to say that you can't add "ing" behind the verb.If you do that,you will mistake.
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