Question

He met a French girl when he was______________ the London School
of Economics.

Answer 1

Answer:

He met a french girl when he was in the London school of Economics.

..thank u

Answer 2

Correct word to be filled is - at

He met a French girl when he was "at" the London School of Economics.

The word filled here is called preposition in English grammar.

The word "at" is used to indicate specific places.

"At" is also used before public places and while writing address.

So, since the college is a public place as well as address, "at" will be filled in the blank.