柴油机排气阀在下止点前打开，其主要目的是（）。
A．排尽废气多进新气
B．减少排气冲程耗功
C．减少新气废气掺混
D．增加涡轮废气能量
参考答案：A
After the Shenzhou-9 manned spacecraft was successfully launched, Liu Yang became the first woman astronaut ________space in China.
A．to enter
B．enter
C．entering
D．entered
井位校正
