His suggestion made me angry, but .
I can still remember that it is since the 1990’s, _____ we began to use cell phones,_______ the number of mobile users has greatly increased.
—I can never forget the day ___ we spent together in the summer camp.—Well, especially the day _______it suddenly began to rain in the middle of the night.
Every one of us must know this: _________ we live can we save the earth.
During the period of recent terrorist activities, people _____ not to touch an unattended bag.
—What a great cook your sister is! —Yeah! We ______ never have enough of her cookies.