真菌是最重要的真核微生物，它们有什么特点？

已知月球到地球的距离为3.84×10⁸m从地球向月球发射一束激光信号，经过月球反射返回地球共需多少时间？

具有健脾渗湿、宁心安神功效的药物是（）。
具有健脾燥湿、止汗安胎功效的药物是（）。

A.茯苓

B.薏苡仁

C.白术

D.猪苓

E.泽泻

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.

甲状腺功能亢进时，腹泻的主要发生机制是（）

A.肠蠕动增强

B.肠内容物渗透压增高

C.肠腔内渗出物增加

D.肠液分泌增多

E.VIP的作用

气相色谱分析的主要特点（）。

A、高效能

B、高选择性

C、高灵敏度

D、应用范围广