（-2m-n）2= ．
（-2m-n）2，
=（-2m）2+2×（-2m）（-n）+（-n）2，
=4m2+4mn+n2．
故答案为：4m2+4mn+n2．
现浇混凝土水池施工技术中，混凝土浇筑完成后，应视气温与混凝土的硬化情况适时覆盖并洒水养护，时间不少于规定的( )d。
A．13
B．14
C．15
D．12
I waited for her at the bus station for two hours, but she never______.
A．turned on
B．turned to
C．turned up
D．turned down
