You can only be sure of _____ you have at present; you cannot be sure of something _____ you might get in the future.
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.
A group of _________ are talking with two ___________.
The team ________ having a meeting .