Question

Ten years (pass) since I met you last.
Correct tense...

Answer 1

The right answer is: Ten years have passed since I met you last.  

Here present perfect tense is used because the effect of time is still there and the total amount of time is calculated on that.

Ten years is a plural number and hence have is used.  

The use of present perfect tense has added a clarity in its time calculation.

Answer 2

Answer:Ten years have passed since I met you.

Explanation:

The above sentence is in present perfect tense. Its order is - sub + have/has + verb in past participle + object. Since the action is done in the past but the result is still with us , we use the present perfect tense.

HOPE IT HELPS YOU.