甲、乙两数是互质数，它们的最大公因数是[ ]
A．0
B．1
C．2
答案：B
It is in the library, you ______ talk loudly. [ ]
A. may not
B. can't
C. needn't
D. mustn't
下列哪一项指标可作为卵巢癌转移的指标？（）
A．CEA
B．AFP
C．CA125
D．癌抗原
E．CA19-9
