Tom, clean up the broken glass _________ someone walks on it.
My friend, Tom, left New York in 1976 and _____ since then.
China _____ a sharp increase in the number of Social Networking Services users in the past years.
The two giant pandas are so much alike that it is impossible to ________ one from the other.
—Did you look up the time of the trains to Shanghai?—Yes, the early train is ________ to leave at 5:30 am.
________ ,loss implies gain; on the other hand, gain implies loss.