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.
Your mother will be ____ until she hears you are safe.
I often heard the song _____ in English.
---- Were all the passengers on the bus injured in the accident sent to hospital? ---- No, _____ only the four who got hurt seriously.
The elderly need special care in winter, as they are_____ to the sudden change of weather.
----I’ve looked everywhere, but I haven’t found any black ink. ----Then, I’m afraid there is ________left.