How many flights leave each day? vs How many flights do leave each day?

[Pam]

When making a question with a Wh word and simple present tense, we usually use "do" or "does." However, this one caught me... What is the problem?

How many / flights / leave each day

This is correct: How many flights leave each day?
This seems very wrong: How many flights do leave each day?

yet: How many / cookies / you / eat / at lunch

How many cookies do you eat at lunch?
and How many cookies you eat at lunch? is clearly wrong!

I meet my class tomorrow morning. I need some good answers before then :)
Pam

[Mister Micawber]

.
How many flights leave each day-- 'Flights' is the subject of the verb.
How many cookies do you eat at lunch?-- 'Cookies' is the object of the verb.
.
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Native English teacher at Mister Micawber's