do you really answer, teachers??

[jasirah]

please i need your views now about my first querry.
tell me why i can't use 'is' in this sentence instead of does


HOW MUCH ---- IT COST TO SEND A LETTER IN CANADA?


when i go to the market, i usually ask the seller

HOW MUCH IS IT?

What is their difference?

[Tdol]

When you have is + a verb, the verb will be in the -ing form:
Where is she going?
We don't use cost in that form. There's no difference in meaning between the two questions- they're alternatives ways of asking the same thing.