市场上有“葡萄糖酸锌”“加碘食盐”“高钙牛奶”“加氟牙膏”等商品，这里的钙、碘、氟、锌是指[ ]
A．分子
B．原子
C．单质
D．元素
答案：D
The day before yesterday the police including one officer ____ searching for the murder in that mountain.[ ]
A. is
B. were
C. are
D. was
如右图所示，△ABC是等腰直角三角形，AB=12，AD的长度是CD的2倍，四边形EBCDA与△AED的面积之比为3:2，问AE的长度是多少()
A．6.9
B．7.1
C．7.2
D．7.4
