战备等级分为（）一级战备、二级战备。
A、经常性战备
B、一般战备
C、三级战备
参考答案：A
The teapot ______ for keeping tea hot after it ______.[ ]
A. was using; was made
B. was used; was made
C. using; is making
D. uses; makes
在我国青春期的学生缺铁性贫血的现象很普遍，约有（）的学生患有缺铁性贫血。
A、1/2
B、1/3
C、1/4
D、1/5
