问题
选择题
Generally speaking , ______according to the directions , the drug has no side effect .
A．when taking
B．when taken
C．when to take
D．when to be taken
答案
答案：B
当分词的逻辑主语也就是主句的主语，这时可以省去逻辑主语和be动词.现在分词表示主动和进行，而过去分词表示被动和完成。在这个句子中，其实是when the drug is taken,省去了the drug is，the drug 和take是被动关系．