present perfect

[Monik2]

If I use the time word today...can I use present perfect


Ex:I have worked today
Or: I worked today

The most important thing to remember about the present perfect is that it can never be used with adverbs which describe finished time periods,


Thaks
Monik

[rewboss]

By definition, "today" can never be a time in the past. The present perfect is a present tense -- that's why it's called the present perfect -- and describes the present.

That is, it refers to the result of a previous action.

"I worked today" is just part of a story: "I worked today, and then I went home, had a meal, watched TV..."

"I have worked today" means: "I don't need to work any more." Or: "I am tired."

[dihen]

Is "He seems to have been sick yesterday" incorrect?

[Tdol]

It's correc- the perfect infinitive form is not the same as the present perfect. The form yuou used just shows that the action is complete, and can be used with past time reference.