Directions: Complete the following MCQ using an appropriate preposition.
He is very weak __________ Geography but is good __________  all other subjects.

The correct answer is: In, At

The correct answer is "in, in".
We use the preposition "in" to convey the idea of either a surrounded area or a specific measure of time, that is, any month or year. Here, the speaker is talking about his good performance in the field of Geography and bad performance in the ret of the subjects. Here, the inclusion is not within a physical land area, but within the complete aspects or boundaries of knowledge. Though no specific time is mentioned here, a specific inclusion within the field of knowledge has been mentioned both in the case of Geography and other subjects. So, the correct answer is "in, in".