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