第17题: [单项选择]牙周病患者在何时可以进行正畸治疗() A. 任何时候牙周病患者都不能进行正畸治疗 B. 只要控制牙周病后就可进行 C. 只要牙槽骨吸收不到1/2时,就可进行正畸治疗 D. 牙周病患者牙槽骨吸收不到1/2时,控制了牙周病后方可进行正畸治疗 E. 牙周病患者任何时候都可进行正畸治疗 参考答案:D
Why are the bus tickets much cheaper than the train tickets A. The bus trip takes longer time. B. The bus stops at several cities. C. Few people enjoy bus trip. D. There is no rest room in the bus. 参考答案:A