You will find concentrating on active and useful words the .

问题描述：

You will find concentrating on active and useful words the ..语法问题
You will find concentrating on active and useful words the most effective route to enlaring your vocabulary.
语法问题：这句中的concentrating 为什么要用ing ?
还有 enlaring 为什么要用ing?

1个回答分类：英语 2014-12-01