对原发性肝癌诊断有价值的指标为 ()
A.AFP
B.CA15-3
C.NSE
D.PSA
E.CA125
参考答案:A
The old man ________ all his free time in collecting stamps. [ ]
A. costs
B. pays
C. spends
D. too
闸阀开启后应保留旁路阀在开启状态。