城市主要供水的水源地，应在何处布设断面？
A、上游500m
B、上游1000m
C、下游500m
D、下游1000m
参考答案：B
________ of giant pandas is getting _________ because their living areas are becoming farmland.
A．The number, larger and larger
B．A number, larger and larger
C．The number, smaller and smaller
D．A number, smaller and smaller
原发性肝癌常用的标志物是（）
A.CEA
B.AFP
C.PSA
D.铁蛋白
E.CA-125
