You had one of your teeth pulled out yesterday, ______? 

 I heard that some patients who had undergone laser eye surgery experienced sudden losses of vision, ______?

--He must have received a good education in his childhood, ________ he?--________, he is polite and well-behaved and acts like a gentleman.

–Alice, feed the bird today, _____?--But I fed it yesterday.

一______are you staying in Tibet?—Just for four days．