Question

CORRECT THE ONE GRAMMATICAL MISTAKE : 1_The teacher always tell us to have high spirits in case disaster .
2_My professor was telling us about how he is going to achieve his goals when the principal enter the room.
3_While I was thinking about how to overcome my problems, my father talked to me.
4_Mr.James like to have his periods in the morning to cheer his students up.

PLEASE ANSWER MY QUESTIONS I GIVE BRIANLEST
PLEASE don't write all only the mistakes