1. He will must go to Japan. (X)

Question

2. He will have to go to Japan.

3. She will may go to the amusement park.(X)
4. She will be allowed to go to the amusement park.

5. He must can speak Chinese.(X)
6. He must be able to speak Chinese.

7. He may must parctice speaking German.(X)
8. He may have to practice speaking German.

9. He may can go abroad.(X)
10. He may be able to go abroad.
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In each pair, is the second one grammatical?

Answer 1

yes

Answer 2

The second one is grammatical. The first of each pair is not.

Answer 3

yes