Le siècle ________ la bombe H et les antibiotiques ont été inventés est le XXème siècle.

Question

I had written 'dans lequel', but received a wrong answer.

In reading the lesson, it stated that after a noun 'dans lequel/le' can be used instead of 'où'.

Why is 'où' the only answer here?

thank you. Jennifer

Accepted Answer

Hi Jennifer,
"Où" in French can be used to translate "Where" or "When". 
In the example you mention, you cannot use "dans lequel" as "où" was used to express "when". See below a quick recap:
 
"Où" means "where":
You can use "dans lequel" to introduces an action taking place in a previously mentioned location. ("The town where I lived"/"La ville où j'ai vécu"/"La ville dans laquelle j'ai vécu")
 
"Où" means "when":
When "où" refers to actions happening in a time frame, it will be used to translate "when". ("The day when I won"/"Le jour où j'ai gagné")

Answer

merci Marie...