I wonder when it’s possible to use the Past Simple and the Present Perfect in the following sentences:
I was busy as a bee this morning.
I have been busy as a bee this morning.
I presume the Past Simple is used when the speaker says that in the afternoon or in the evening. And the Present Perfect can be used until the end of the morning.
That’s a reasonable rule of thumb for that sentence, Irene, but it is not really quite as simple as that, and you should not apply the same rule in all cases.
The colon is used to indicate that what follows it is an explanation or elaboration of what precedes it. A colon can introduce a list. It just happens to be a list of sentences under discussion in that post.