— Why are you in such a hurry?
—I am dying to see my brother. He is coming back home tonight.
A：can't wait to
B：remember to
C：allow myself to
判断△ABC的形状：____
①声纳系统是利用超声波工作的
②声纳设备是利用次声波工作的
③超声波不能在海水中传播
④声呐系统是利用回声原理工作的
——Where is the new student ?
——America.
