Laughter, along with an active sense of humor, ______ protect you against a heart attack, according to a recent study.
| A．have helped | B．helped | C．help | D．helps |
When asked why he prefers bikes to buses, the professor said, “Riding a bicycle takes __________ half an hour, but it’s more convenient and environmentally friendly. ”
| A．absolutely | B．accurately | C．approximately | D．exactly |
I like __________in the early morning when the air is fresh and I can take a walk around the garden.
| A．that | B．it | C．which | D．what |
Beijing was attacked by such a terrible sandstorm __________few citizens has ever experienced before.
| A．where | B．as | C．when | D．which |
It was announced that only when the fire was under control __________to return to their homes.
| A．the residents would be permitted |
| B．had the residents been permitted |
| C．would the residents be permitted |
| D．the residents had been permitted |
—Why didn’t you help him?
—I __________, but I didn’t have the money.
| A．I did have | B．I would have | C．will have | D．must have |