基本大类是图书分类表中首先区分出来的（）类目
A、第一级
B、第二级
C、第三级
D、第四级
参考答案：A
交通信号灯由红灯、绿灯和黄灯组成
When asked why he prefers bikes to buses, the professor said, “Riding a bicycle takes __________ half an hour, but it’s more convenient and environmentally friendly. ”
A．absolutely
B．accurately
C．approximately
D．exactly
