下列每个句子中均有一处错误，请找出并改正。

小题1: We don’t know that we can do about it.

小题2:Could you tell me how I could get to the nearest post office?

小题3:The old man said he had joined the army in 1965.

小题4:Mary said she did not heard from her old classmate since September.

小题5: Charles asked he could use my car.

小题6:Mother asked me where I will go the next day.

小题7:Do you have a friend whom you could tell everything, like your deepest feelings and thoughts.

小题8:Don’t look at someone else paper, John. You should do it by yourself.

小题9: In order to improve your English, you can try writing an English diary every day.

小题10: The teacher gave a series of example in her lecture in order that everybody could understand.