下列地形类型中，海拔一般在500米以上，地表峰峦起伏、坡度较陡的是 [ ]
A．盆地
B．山地
C．丘陵
D．高原
答案：B
基准剂量仪的零点漂移的允许精度为（）
A.≤±0.1%
B.≤±0.2%
C.≤±0.5%
D.≤±1%
E.≤±2%
There are 450 birds at a small zoo. The number of birds is 5 times the number of all the other animals combined. How many more birds are there than non-bird animals at the zoo ？（）
A. 400
B. 360
C. 270
D. 180
E. 90
