have or must?

[Murzim]

English Language Tests, Intermediate level

ESL/EFL Test #789 "Grammar Crunch (5)", question 5

I failed the last exam so I really ......... to do well on this next one.

(a) must
(b) should
(c) can
(d) have

English Language Tests, Intermediate level

ESL/EFL Test #789 "Grammar Crunch (5)", answer 5

I failed the last exam so I really have to do well on this next one.

Correct answer: (d) have
_________________________

have or must?

Murzim

[Mister Micawber]

'Have to do'. 'Must to do' is impossible grammar.
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Native English teacher at Mister Micawber's