at home : 解析:　　at home 出现的频率很高,意义也很多,如be at home(在家),at home and abroad(国内外),make oneself at home(使某人轻松自在无拘束,就像在自己家一样),be(或feel)at home(感到安适,无拘束),be at home in sth.(熟练掌握某事物,精通某物)。例如:
Make yourself at home!别拘束(放轻松点,就像在自己家一样)。
I didn’t feel quite at home then. 当时我感到一点都不自在。
I prefer to buy a car made at home. 我宁愿买一辆国产的小车。
Is it difficult to feel at home in a foreign language? 精通一门外语难吗?
The Canadian named Dashan is at home in Chinese. 这位名叫大山的加拿大人非常精通汉语。