主棱

在做氢气验纯实验时，下列操作正确的是[ ]

A．直接在发生器的导管口点燃，观察是否能安静地燃烧

B．用向上排空气法收集一试管氢气，然后移近火焰试验

C．用排水法收集一试管气体，经检验没有听到声音，则说明氢气纯净

D．用向下排空气法收集一试管气体，经检验不纯后用拇指摁住一会儿，再重新收集

Alexis was hot and tired. With rage in her voice she shouted, "Pull me up！I give up, I hate this. This is stupid!" It was at that moment when Jason, the adviser on the trip, looked at me and said, "Ed, I'm going to go down and talk with her." I then shouted down to Alexis, "Hold on! You can do this. We know you can!"

Jason grasped another rope, put his climbing harness(系带)on and began to repel down the cliff. Within moments Jason was beside Alexis. She had her cheek directly against the face of the rock with her feet barely resting on a small piece of the cliff that jetted outward. Jason said to Alexis, "I know that you have been on this cliff now for what seems like a long time. Your feet and fingers are cramping(痉挛)up and your forearms feel as though they are on fire. But , Alexis, you are strong, look how far up you are already. You have taken one of the more difficult paths up the cliff. Look Alexis, look at the path you have taken."

At that moment, Alexis moved her cheek away from the rock face and looked down. The bright white chalk she used on her hands to give her a better hold, showed the path where her tired hands had moved her upward on the cliff. Jason was right. Alexis had taken the hardest way up the cliff. Jason then looked straight into Alexis' eyes and in a calm voice he said, "You are not alone out here, there are people who care about you, who want to help you and see you succeed. We are going to do this together. Are you ready?" Slowly she shook her head yes and took a deep breath.

小题1:Jason went down the cliff because _________.

A．Alexis took a wrong path

B．Alexis was trapped in rocks

C．Alexis didn't believe in herself

D．Alexis' forearms were badly hurt小题2:We can infer from the passage that ________.

A．Alexis was finally pulled up by Ed

B．Alexis regretted having taken the wrong path up the cliff

C．Alexis was immediately sent to hospital after she was pulled up

D．Alexis successfully rock climbed小题3:The underlined word "hot" in the story means _________.

A．disappointed

B．angry

C．uncomfortable

D．running a high body temperature小题4:Alexis would probably become _________.

A．more strong-minded

B．easier to give up

C．poorer in health

D．less interested in rock climbing

中国的技术创新经历了那几个阶段？

商品房预售前，房地产广告的主要目的和重点应是（）。

A、提升商品房的价值

B、提高商品房的知名度

C、提升商品房的品质

D、降低商品房的后期开发成本

甲乙双方签订一买卖合同，合同金额为4万元，付款方式为托收承付、验单付款。卖方甲根据合同规定发货后委托银行向买方乙收取货款，乙的开户银行于2009年5月15日 (星期一)收到经甲的开户银行审查后的托收凭证及附件，当日通知乙。承付期满日，乙的账户上无足够资金支付，尚缺2万元。同年5月29日，乙存入3万元。根据《支付结算办法》的有关规定，乙应被计扣赔偿金的数额为( )。

A．120元

B．140元

C．150元

D．110元