题目

Yuan Longping a famous Chinese scientist, is doing research on sea rice. If farmers ___start planting rice in salty water, China's food will surely rise. A . can B . can't C . must D . mustn't 答案：A如图所示，嫦娥一号卫星成功实施了三次近月制动，顺利完成“太空刹车”动作，建立了正常的姿态．在制动过程中嫦娥一号的机械能    （填“增大”、“不变”或“减小”）．