"He must be in the room". "He must be inside the room" what is to be be used?

Question

"He must be in the room."

"He must be inside the room."

• Which one is correct?

• Which preposition is suitable for this sentence?

  I think, "He must be in the room." This one is usually used.

Answer 1

Yes, "in the room" is more commonly used. "inside" is not wrong, but it's a longer word that adds no more meaning (at least when used in reference to a room.)

You would use "inside" as a contrast to "outside", for instance, as in the following which makes an implicit reference to a house...

A: "It's cold outside."

B: "Come in; it's warm inside."