请教：分词与从句修饰的区别？ 补充题27

woodorstone

我也不明白，og解释里说：

Choice A can be faulted because having bought on margin does not precisely establish a sequence of events; who had bought on margin is needed to indicate that the speculators made their purchases before there were declines in the market and before they were forced to sell.

但我看到语法书里说：

The tense of a participle is determined by the tense of the verb in the predicate.The present participle show action occurring at the same time as that of the verb.The past participle and the present perfect participle shows action occurring earlier than that of the verb.

好困惑。。。

另外，请教NN, 为什么the present perfect participle 不能修饰名词呢？

fannyyudan

这个OG里又有的！有谁能把全部解释贴出来看看呢！