1. You will must go hunting. (X)

Question

2. You will have to go hunting. (O)

3. He may can lift the rock.(X)
4. He may be able to lift the rock. (O)

5. She must can solve the math problem. (X)
6. She must be able to solve the math problem. (O)

(Are the marks, X's and O's, used correctly?)

7. She may will go to London tomorrow.

8. She may be going to go to London tomorrow.

9. She will may go to London tomorrow.
10. She will _________ go to London tomorrow.

(Which ones are grammatical? What words can be put in the blank?)

Answer 1

2, 4, 6 and 8 are correct.

10. possibly, probably, likely?

Answer 2

There are two sets of auxiliary verbs (helping verbs) to make a variety of English tenses. The set that 1) helps us make progressives, futures, and possibilities, and the set that 2) helps us make the perfect tenses.

This webpage does a pretty good job of explaining some of them and their uses.
http://grammar.ccc.commnet.edu/grammar/auxiliary.htm

Basically, you can combine some in set one with some in set two, but rarely can you combine those in set one with another from set one.

I hope that makes sense!