past perfect

New2grammar

Huevos, could you give a couple of examples to support your statement.

Bob went home because his wife had fallen over in the shower and broken her leg.

Bob went home because his wife fell over in the shower and broke her leg.

 

Bob used to play a lot of tennis when he was younger.

Bob played a lot of tennis when he was younger. 

 

Bob has been to the Post Office this morning.

Bob went to the Post Office this morning.

New2grammar

Are the first sentences what you said grammatically preferable?

Yes, but Americans have become so lazy with perfects that these days it is quite acceptable for them not to use the perfect here at all. 

New2grammar

However, the third first sentence is ,as far as I know, grammatically incorrect.

"Has [something] this morning" (present perfect) is fine grammatically. The state caused by the event prevails to the present, i.e. "This morning Bob has eaten a full English breakfast so it's unlikely he's going to want to take lunch early".

New2grammar

That's not what I was taught.

What were you taught?

By the way it was ok for Shakespeare: Hadst thou done so, the kings that have revolted, and the soldier that has this morning left thee, would have still followed thy heels. 

New2grammar

I was told that present perfect tense should not go with a point in the past.

That's correct but it can be used with any current temporal marker, i.e. this morning , today, this afternoon, this evening, this week, this month, this year, etc.

From "A Grammar of the English Language", Volume I, 65B: A minute before 12 o'clock in the morning we may say 'I have bought a new hat this morning'. A minute later this morning is gone forever and this afternoon is ushered in. After the bell taps twelve we must say 'I bought a new hat this morning'. Thus the present perfect distinguishes sharply between the past and the present. It can never be used for something in the past.

 I hope that helps clarify.