这个问题太笼统了,你再具体一点儿
简单回答是:WILL用于一般将来时,后面加上动词原形
HAVE 后面加上动词的过去分词是现在完成时,也有一些关于HAVE的固定词组:have a rest,have breakfast,have classes等等.
BE 就是am is are 可以是一般现在时如:she is a teacher.I am a boy.They are friendly.
也可以是现在进行时,如:she is swimming.I am watching Tv.They are playing basketball.注意现在进行时的BE后面一定要有动词的现在分词.