time clause

[sergeyrais]

Will it be grammatically correct to substitute the Present Perfect for the Present Simple in the time clauses of the following sentences?

When we have had tea, we'll go for a walk.
When we have tea, we'll go for a walk.

Are both of the sentences right or not?

[SoothingDave]

Both are grammatically OK, but they mean different things.

[sergeyrais]

Dear SoothingDave
could you specify the difference in meaning, please?

[emsr2d2]

#1 means we will go for a walk when we have finished having tea.
#2 means we will go for a walk at the same time as having tea (an unlikely situation).

If you replace "When" with "After" in both sentence, they will mean the same as #1.

After we have had tea, we'll go for a walk.
After we have tea, we'll go for a walk.