会议设备所用的电源电压范围应在（）。 A.140V±20V B.140V±40V C

阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

David: Have you made up your mind  小题1: to go for your holiday, Jane?

Jane: We  小题2:  (go) to Florida.

David: Great! Florida has always been one of the world’s most popular tourist      小题3:    (attract). Oh, by the way, how long are you going to stay there?

Jane: One week.

David: Have you got any friends there?

Jane: No. I have always wanted to go,    小题4:  I’ve been too busy to afford the time. Now I’ve got a week’s holiday, and I can enjoy Christmas special prices. My dream will come true.

David: Lovely! I guess you will    小题5: (certain) go to Disneyland.

Jane: You are right. You have been there, right?

David: Yes, I went there last year. And I’m looking forward    小题6:  going there a second time.

Jane: Tell me something about it, will you?

David:  The park,    小题7:  is often called a “Magic Kingdom”,   小题8:  (make) up of several main sections. They are named Main Street, Frontier Land, Fantasy Land, Tomorrow land and Adventure Land. There are so many things    小题9: (see) in the park.

Jane: It must have been 小题10:  unforgettable experience for you.

David: That’s true. I’m sure you’ll enjoy your visit.

Jane: Thank you. I believe so.

张骞出使西域后，丝绸之路渐趋形成。该商路的起点是[ ]

A．洛阳

B．长安

C．敦煌

D．疏勒

将5mol/L的Mg（NO₃）₂溶液a mL稀释至b mL，稀释后溶液中NO₃^－的物质的量浓度为

A．mol/L

B．mol/L

C．mol/L

D．mol/L

如图是长江源头到入海口的地形剖面图，读图回答各小题。

小题1:长江上游主要的生态环境问题是

A．水污染

B．泥沙淤积

C．洪涝灾害

D．水土流失小题2:长江从上游到下游所流经的地形区依次是

A．青藏高原、四川盆地、横断山区、长江中下游平原

B．青藏高原、横断山区、四川盆地、长江中下游平原

C．横断山区、四川盆地、青藏高原、长江中下游平原

D．长江中下游平原、四川盆地、横断山区、云贵高原小题3:长江的水能资源主要集中在上游河段，其原因是

A．支流多

B．落差大

C．河道曲折

D．水量丰富小题4:长江最大的水利枢纽工程是

A．三峡

B．二滩

C．小浪底

D．葛洲坝

电泵机组下井前，电机部分是从电机尾部（）注油，要求摇动注油泵的速度为（）圈／1分钟，直到电机顶部出油，再重复（）次，每次间隔5-10分钟，确保电机内腔气体排净。