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问题 单项选择题 A1/A2型题

酮体是指（）。

A.丙酮+乳酸+乙酰乙酸

B.丙酮+β-羟丁酸+乙酰乙酸

C.丙酮+β-羟丁酸+草酰乙酸

D.丙酮+醋酸+草酰乙酸

E.丙酮+丙烯酸+乙酰乙酸

答案

参考答案：B

解析：酮体是乙酰乙酸、β-羟丁酸、丙酮三种物质的总称。

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

针对高层住宅建筑，防火云梯高度多在( )之间，我国目前高层住宅的高度即是参考这一情况决定的。

A．10～30m
B．20～40m
C．30～50m
D．50～70m
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