It is high time for us to take measures to protect these old traditions and customs before they ___.
She has been in Tianjin for ten years. Tianjin has become her second _________.
________ mothers couldn’t go to the meeting, because they have gone to Shanghai .
Li Lei has been to __________ many times this month.
He is a success as a leader but he hasn’t ________ in teaching.
A classmate of _________ was here ten minutes ago.