按照绝热材料分类，硅藻土、蛭石加石棉类应属于( )。
A．高温用绝热材料
B．中温用绝热材料
C．常温用绝热材料
D．低温用绝热材料
参考答案：A
按规律填数．
①60，30，15，______；
②O.3，0.9，2.7，______．
It's not highly recommended that a dictionary be at hand when English learners _____ some new words. [ ]
A. come out
B. come about
C. come along
D. come across
