Which of the following tips may be helpful in maintaining a good friendship?

A、 “A friend in need is a friend in deed.” No matter what difficulties you encounter, you can always depend on your friend to help you.
B、Because of the tight schedule you may have, it’s not advisable that you should set aside some time for your friends..
C、We should be grateful to what friends have done for us.
D、No matter what our friend asks us to do, we should not hesitate to do it.