铝在火中很难熔化，氧化铝放在水中的状态是什么？
参考答案：氧化铝放在水中的状态是不溶解
How many ____ are there in your family? [ ]
A. people
B. peoples
C. the people
_____ we stood at the top of the building，we were able to enjoy the town below clearly.
A．As
B．Although
C．Unless
D．Until
