—Could you mail these letters for me please?—_____ letters? Your friends are going to be very happy to hear from you again.
Scientists say it may be five or six years _____ it is possible to test this medicine to human patients.
At last we reached a lonely village, _______ a beautiful river.
It was the training ______ he had as a young man _____ made him such an excellent speaker.
---Why did you leave that position? ---I a better position at IBM.
--Have you got the leaving time of the train for me? ---Yes, but you’d better ____of it by yourself.