题目

Tom and Tim are twins(双胞胎) .They’re four years old. It’s difficult for people to tell who is Tom and who is Tim. _____________ The two boys like to jump, draw pictures and play ball games. ___________But they don’t like to take a shower .Today , Tom and Tim come back from outside. _____________ After twenty minutes, Tom goes out. _________Their mother takes Tim into the bathroom. But the boy doesn’t want to go in.“ No ! No! Mom , I’m Tom. _______ ” “ Shut up（闭嘴） ! I know you are Tim. ”At that time, the boy out of the bathroom（洗澡间） is so happy, because MH370失联事件后，澳大利亚派出 “蓝鳍金枪鱼-21”水下航行器，利用侧扫声纳系统描绘出海底详细地图，寻找飞机残骸．金枪鱼-21的最大潜水深度为4500米，水下最大航速为7千米/小时，在水下续航时间为25小时．以下说法不正确的是    A．“蓝鳍金枪鱼”下潜过程中受海水压强逐渐增大 B．“蓝鳍金枪鱼”每次下水可绘出约一百多公里海底地图 C．声纳使用超声波工作，超声波在水中传播速度340米/秒 D．“蓝鳍金枪鱼”在海水中水平航行时，浮力等于重力