Question

非谓语动词语法怎么判断逻辑主语？ （compare）with what I saw 20year

非谓语动词语法怎么判断逻辑主语？
（compare）with what I saw 20years ago,ads today are becoming increasingly popular

Answer 1

主句的主语是ads，那么compare的动作肯定是被动(ads本身不能比较，是人来比较），所以，此句的非谓语动词用
compared with.....

追问

除了语态。要不要看时态

追答

注意主从句一致就行了。

追问

You have to work in this position for two years before being promoted为什么不用promoted

追答

before这里不是连词，而是介词，当然要用 being promoted了。

如果是连词的话，就相当于一个状语从句，即：before he is promoted。

追问

Being done是现在分词进行时。这里用合适吗！

追答

你抽空看看张道真的语法书有关于非谓语动词部分。being done可以看成是现在分词的被动形式或者过去分词的进行式。
非谓语是个对中国学生来说比较简单却用起来比较复杂的语法现象，要想弄懂它，你一定要细心地把三种形式（to do/ doing/ done)系统地反复地研读几遍，慢慢地根据例句进行对比，你就会清楚它们的用法及区别。

追问

Judging by the look on his face,he doesn't quite understand what the speaker is saying

怎么不用judged

追答

很好的问题：建议你看一看朗文高阶辞典judge词条下的解释，你就会一目了然。
这里应该是ing形式做介词用，就像including/ considering等一样。