in是介詞,介詞後面必須接名詞,代詞或者動名詞,即doing。
例句：
These laws are in effect in twenty states.
這些法律在二十個州有效。
On the day in question we were in Cardiff.
在所說的那一天，我們在加的夫。 擴充套件資料
They were killed in a high-speed crash in a tunnel in Paris.
他們在一起發生在巴黎一座隧道里的高速行駛引發的撞車事故中喪生。
In her speech, the senator came out in favour of a change in the law.
這位參議員在她的'講話中公開贊成修改法律。
The rise in interest rates was not reflected in a corresponding rise in the dollar.
利率上調沒有反映在相應的美元增值上。
They lived in rooms in Kensington.
他們住在肯辛頓的出租房間。
We went skiing in France in March.
三月份我們去法國滑雪了。
in是介詞,介詞後面必須接名詞,代詞或者動名詞,即doing。
例句：
These laws are in effect in twenty states.
這些法律在二十個州有效。
On the day in question we were in Cardiff.
在所說的那一天，我們在加的夫。 擴充套件資料
They were killed in a high-speed crash in a tunnel in Paris.
他們在一起發生在巴黎一座隧道里的高速行駛引發的撞車事故中喪生。
In her speech, the senator came out in favour of a change in the law.
這位參議員在她的'講話中公開贊成修改法律。
The rise in interest rates was not reflected in a corresponding rise in the dollar.
利率上調沒有反映在相應的美元增值上。
They lived in rooms in Kensington.
他們住在肯辛頓的出租房間。
We went skiing in France in March.
三月份我們去法國滑雪了。