Has Or Have ?

What are the capital cities that have a population of more than 100 million people?

'have' agrees with 'cities' ( The city has / the cities have)

a population because we don't know the specific population you are talking about.

E.g The population of England is....

We don't use plural with number + hundred/thousand/million.

E.g. Three hundred / five thousand / six million /
BUT Hundreds of people / thousands of words / millions of stars

What are the capital cities that have a the population of more than 100 millions people ? - more than one city so have

Which capital city (only one) has a population of more than 100 million people?

Thank you, everything is clear except what you mean by that "a population because we don't know the specific population you are talking about." ? If the number of something is unknown we should use "a" instead of "the" ? Thanks

The population of London
London has a population of 10 million people
The population of London is 10 million.

Sorry, I didn't explain that very well. Articles are one of the most difficult grammar points to master. Sometimes it's better to remember set expressions.

We always say to have a population of not to have the population of.

And the population of ______ is .... not a population of _____ is......

First I think we should use 100 million instead of 100 millionS. Second I do not think you need the word "people" becasue "population" here means the number of people.

Third I have several options, can anyone make commonts to each of them? Thanks.

1) What are the capital cities whose population is more than 100 million.

2) What are the capital cities whose populations are more than 100 milllion.

3) What are the capital cities having population more than 100 million.

4) What are the capital cities having a/the population more than 100 million.

5) What are the capital cities having populations more than 100 million.

Thanks a lot.

In this case it don't need the people but in other case, we need that quantity such as
what are the countries that have an area of more than 1000 meter square.

If you take away "meter square" it would become ambiguous.

Thanks

Of courser. Area in your context can be used with many units, but population in most of contexts can only mean the number of people or animals.