什么叫单行晶和聚行晶?
参考答案:
单行晶:由形状相同、大小相等的晶面聚合形成的形体。共有47种单行,常见14种。
聚行晶:由两个或两个以上的单行聚合而成的形体。
这一组交通警察手势是什么信号?
A、左转弯信号B、停止信号C、右转弯信号D、靠边停车信号
--Laura didn’t join in their dancing last night , did she ?
---________________, because she fell off her bike and hurt her legs
A.Yes, she did
B.No, she didn’t
C.Yes, she didn’t .
D.No, she did