[Grammar] I've got something to doubt

[moebachelor]

I've got this question sounds "there....something wrong with the food"
as for me there two option possible:
1.must have been
2.might be
my tutor said *1, but why it uses have instead of has?
thanks

 

[2006]

Welcome!

I've got this question sounds "there....something wrong with the food"
as for me there two option possible:
1.must have been
2.might be
my tutor said *1, but why it uses have instead of has?
thanks

Because "have" is preceded by the auxillary verb "must". So you have to keep the base form of the verb, which is "have".

I have... I must have...
(S)(he)(It) has... (S)(he)(It) must have...

 

[moebachelor]

but i think "have" in that sentence is as auxiliary..
...
are there any rules that modals should be followed by base form verbs??
...

 

[Raymott]

but i think "have" in that sentence is as auxiliary..
...
are there any rules that modals should be followed by base form verbs??
...

Yes. Modals must be followed by the base form of the verb.
Can you think of any counter-examples?