A

A LOT, ALOT, and ALLOT
Wrong: My teacher corrects my spelling alot.
Correct: My teacher corrects my spelling a lot.
Tip: Your teacher should allot even more time to that thankless task.

12:00 A.M. and 12:00 P.M.
Wrong: Time of death was 12:00 a.m.
Correct: Time of death was noon (or midnight, depending on the intent).
Tip: Use a.m. between midnight and noon and p.m. between noon and midnight.

5 A.M. IN THE MORNING
Wrong: My breath freshener expired at 5 a.m. in the morning.
Correct: My breath freshener expired at 5 a.m.
Correct: My breath freshener expired at 5 o'clock in the morning.
Tip: The notation "a.m." is Latin for ante meridiem, indicating morning.

AND ALSO
Wrong: And also, I had to take the bus again!
Correct: Also, I had to take the bus again!
Tip: Once is enough