The present perfect simple always expresses a link
between the past and the present.

We use the present perfect simple to express:
•			an impact on the present of an action or a state in
		the past.

		Example:
		I've forgotten to post this letter. Could you remind
		me to do it?
		The shop has been closed for weeks. I have to go
 		shopping elsewhere.

•			a state or an action that has begun in the past and
		continues until the present.

		Example:
		He's been very helpful recently.
		I've never smoked.