某种云有如下特征：云体浓厚庞大，云底阴暗混乱，有一个伸向地面的漏斗状云柱。这种云是（）
A.龙卷云
B.高积云
C.浓积云
参考答案：A
用画线词的对应词填空。
1. Her ______ is an English teacher and her father is a Chinese teacher.
2. My sister is in Beijing and my______ is in Chengdu.
3. These are his pens and ______are pencils.
4. This is my ______, Mary. And ______ is my brother, Mike.
5. My grandmother is sixty and my ______ is sixty-five.
在进行安全预评价中可以使用以下哪几种评价方法？（）
A.安全检查表
B.故障类型及影响分析
C.事故树
D.危险指数法
