下列物质熔点最高的是（）。
A.CF4
B.CCl4
C.CBr4
D.CI4
参考答案：D
The car ran into a crowd of middle school students, ______to hospital immediately.
A．two of whom sent
B．two of them sent
C．two of whom are sent
D．two of them sending
如果载客陆上飞机需要一个自动展开滑梯撤离系统，应在何时预位？
