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问题 单项选择题

体免疫系统中能合成并分泌抗体的细胞是（）

A.吞噬细胞

B.浆细胞

C.效应T细胞

D.T淋巴细胞

答案

参考答案：B

解析：浆细胞能合成并分泌抗体的细胞，故选B。考点：本题考查体液免疫，意在考查考生能理解所学知识的要点。

填空题

Beijing: The United States and North Korea had their first ______ in four months here this afternoon as part of the ______ negotiations on how to end North Korea’s nuclear program, but diplomats played down prospects for______. James A. Kelly, assistant ______, and Kim Yong Ⅱ, North Korea’s deputy foreign minister, met ______ of formal discussions, ______ on direct dialogue that began after a stormy meeting ______ in which North Korea warned that it was moving quickly to ______ nuclear arms. The Bush administration had insisted ______ that it would only hold talks with North Korea ______ because, it argued, only ______ pressure would persuade North Korea to______. It got its way when North Korea dropped its insistence on ______ and agreed, after extensive efforts by China, to hold unusual simultaneous negotiations with ______,______,______ and ______ as well as the United States. Though Bush administration officials had not ______ talking privately with the North Koreans during______, the fact that Mr. Kelly and Mr. Kim met on the first day was seen as a sign of ______ by the American side.
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单项选择题

设级数

收敛，则

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