Is my sentence correct ?
My classmates are unhappy. I think they have been tiring in these weeks.
or
My classmates are unhappy. I think they have been tired in these weeks.

Question

Answer

THE SECOND ANSWER IS THE CORRECT FORM TO USE.

Answer

The  'have been tired' in the second sentence is correct but the 'in' before 'these weeks' isn't necessary. Either 'they have been tired these weeks' or even better sounding would be 'they have been tired these last few weeks' (at least in the US).
Hope that helps,
Andrew

Answer

Neither sounds good.

We would say something like 'in recent weeks' or 'in the last few weeks' instead of 'these weeks'. While you will be understood it would never be said as you have said it by a native speaker.

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