下图表示细胞免疫过程中X细胞对靶细胞的杀伤过程,其中能够产生X细胞的是
A.B细胞
B.效应B细胞
C.T细胞
D.效应T细胞
答案:C
By the time these books were published, he _____ addicted to them.
A.had become
B.becomes
C.has become
D.became
领土主权包括:()
A.领土不可侵犯
B.国家在领土范围内享有属地管辖权
C.国家对领土范围内的一切资源具有占有、使用和支配的永久权利
D.领土主权可以让渡