How to use 'many a' and 'a great deal of' in a sentence. How to pronounce 'impasse'

Good morning KIB  earthlings.
Lets get down to brass tacks.

Let's look at the use of verbs. Yesterday someone brought a statement to me and enquired if it were correct.

'many a fellow knows the truth'
Many a driver ploughs this road daily'

'Many a teacher doesn't know how to  English'.

All these sentences are correct.

According to Oxford dictionary,
Many a: ( formal: always used with a singular noun and a singular verb) means a large number of something.
E.g many a young person has experimented with drugs.  

So,  don't pluralise anything in the sentence because there is an 'A' already.

'Many a teachers like to flog their students ' is wrong.

'A great deal'
How do you use 'a great deal'?
A great deal takes a singular verb.
E.g A great deal of bananas is planted in the north.

'A great deal' takes a singular verb. 

Finally,  the pronunciation of impasse is /'ampa:s/
Not (impas)

It's not Enemity,  it's Enmity.
Unkept is wrong(when used for humans ) I'd rather you use 'unkempt' and pronounce it as (unkemt) or (unkempt) / ʌnˈkɛm(p)t/.

Unkept also means untidy and it is basically used for things and places.

The class with King Ifey is done and dusted.

Ciao.