—Do you mind if I smoke here?—______ I feel a bit sick.
________ is known to us, May 12, 2008 was the day _______ Wenchuan earthquake happened.
They _________ have arrived at lunchtime but their flight was delayed.
China is one of the countries ________ the Mekong River flows.
He was _________by his colleagues though he himself didn’t think he had done anything special.
It was reported that a chemical factory________ last night, which killed thirty workers.