战国时期各国中央政府官员中属于中枢官员的有( )A．国尉 B．柱国 C．御史 D．

[2014·宁波质检]化简S_n＝n＋(n－1)×2＋(n－2)×2²＋…＋2×2^n－2＋2^n－1的结果是(　　)

A．2^n＋1－n

B．2^n＋1－n＋2

C．2ⁿ－n－2

D．2^n＋1－n－2

—When did he start playing basketball ?

—He began to play ________, and became famous ________. [ ]

A. in the 1990s,  in his twenties

B. in 1990,  in his twenty

C. in 1990s,  in the twenties

D. in the 1990's,  in his twenty

（）加办回执业务时，回执片应粘贴在邮件背面。

A.平常信函

B.挂号信函

C.保价信函

D.平常印刷品

水的两相变化和平衡的饱和水汽压的判据是什么？

以下何种疾病在甲状腺显像上表现为冷结节或凉结节（）

A.甲状腺腺瘤

B.结节性甲状腺肿

C.甲状腺囊肿

D.甲状腺癌

E.亚急性甲状腺炎