______ acupuncture developed, the simple “bian stones” were replaced first by stone and pottery needles, and ________ by metal needles.
On the third floor there are two rooms,__________ is used as a meeting room.
On a __________ morning the little match girl was found __________ at the corner of the street.
If you don't want to set fire __________ the ship,__________ your cigarette.
-Is that hall big enough? We have at least 200 guests. -Sure. That's a hall which can __________400 people.
Mark needs to learn Chinese __________ his company is opening a branch in Beijing.