过去分词、现在分词被动式、现在分词完成被动式的区别，要具体情况具体分析。就你提供的句子而言，______ (take) in time, this medicine will be quite effective.  这属于分词短语作条件状语的用法。

▲在此情况下，用过去分词taken 即可。转换成从句是If it is taken in time，因为“现在分词被动式”being taken 表示“被动和进行”，所以不符合条件句的要求。

being done 形式不是不可以做状语，而是在什么情况下才可以。例如，以下情况就可以用：

Being watched by so many people then, she felt very nervous at the stage. “当时由于那么多人在观看她，所以她在台上很紧张”。说明“被别人看着”是在进行的状态下。

Being tired out after a long walk, they had to stop at the foot of the mountain for a rest.

作状语时，分词表示“状态”而不是“动作”的情况下，“过去分词”和“现在分词被动式”都可以用，意思几乎没有差别。

▲再看过去分词和现在分词完成被动式的区别：

1. Compared with them, we still have a long way to go. 和他们相比，我们还有很长的路要走。

2. Having been shown around the library, we were taken to the lab. 带着参观了图书馆后，我们又被带去参观实验室。

过去分词”Compared with them 作条件状语，与句子谓语动词发生的时间没有先后之分，或者先后时间不明确。句1相当于If we are compared with them, we still have a long way to go. 而“现在分词完成被动式”Having been shown the library 一定早于句子谓语动词发生的时间，句2相当于After we had been shown around the library, we were taken to the lab. 一般来讲，只要动作早于谓语动词发生的时间，而且又是被动意义，就应使用“现在分词完成被动式”。又如：

Having been bitten twice, the postman refused to deliver our letters unless we chained our dog up. 因为被狗咬了两次，邮递员要我们把狗拴起来，不然就不给我们送信了。（因果关系，原因总是在前，所以使用完成式。）