若实数x，y满足x-y+1≥0x+y≥0x≤0，则z=x+2y的最大值是（ ）A

一个直五棱柱的侧面个数是______，顶点个数是______，棱的条数是______．

某同学用如图所示的实验装置“研究平抛物体的运动”，描绘平抛物体运动的轨迹，求物体平抛的初速度。根据该同学的实验过程，完成下列填空：

（1）在安装器材时，应该使木板在竖直平面内，斜槽末端应该保持在__________方向；

（2）让小球多次从斜槽上同一位置上滚下，目的是为了让小球每次平抛的__________相同；

（3）取下白纸，以抛出点为坐标原点O，以竖直向下方向为轴，水平方向为轴，用平滑的曲线画出平抛小球的运动轨迹。测得曲线上某一点的坐标（，），请用、、g表示小球平抛的初速度=__________。

马戏团表演时常常有绷床节目，演员从高处跳下落在绷床上又被弹起，如图所示．演员从绷床上弹起又落回绷床的过程中，在______处重力势能最大，在______处弹性势能最大（填“最高”或“最低”）．

Online shoppers would rather receive an offer for a product or service than make their own offer ₃ according to a study led by a Michigan State University scholar that has implications for the fast-growing e-commerce industry. The findings may come as a surprise given that shopping online is an anonymous(匿名的）process that seemingly can give consumers more confidence to drive a hard bargain_,said Don Conlon ，Professor of Management in MSU’s Broad College of Business.

But the study found that participants who made their own offers were less successful in sealing the deal and ，when they were successful_? worried they overpaid Many shoppers found the process of researching an offer to be a hassle. “ Americans are very busy，and it’s less time-consuming to be the one receiving the offer rather than the one proposing the offer  ” Conlon said. ^u People tend to be happier when they’re in the receiver role. ”

Online spending in the United States is expected to jump 45 percent in the next four years， from $ 226 billion this year to $ 327 billion in 2017，according to Forrester Research Inc. Nevertheless, researches into this prosperous market remain largely focused on the strategies of companies, rather than those o£ shoppers. Conlon^’s study is ，obviously, a rare exception.

Conlon got the idea for the study after considering the difference between two popular sites for hotels and airline flights, priceline.com, which takes bids, and hotwire.com ，which provides offers. Using these two models ，Conlon and his fellow researchers conducted a series of experiments with more than 850 people who were charged with booking a fictional hotel room and acquiring a fictional antique car. Not only did participants prefer to receive bids, Conlon said ，but they also secured more deals in that receiver role. Further ，when they had to make the bids ，they were left more mentally taxed and regretful.

From an industry perspective，putting customers in the receiver role may help fill more hotel rooms and airplane seats. “If you’re a business with a lot of products₃ ” Conlon said，“you may want to be the one making the offers. ” However, when selling single items, such as an antique car， accepting bids may be a better option since that typically drives up the price, he said.

小题1:What can we learn from Para. 1?

A．The result of the study gives customers more confidence.

B．Scholars aren’t surprised at the findings of the study.

C．Online shoppers don’t bargain as much as expected.

D．E-commerce industry drives more hard bargains.小题2:It can be concluded from Conlon’s experiments that______.

A．online shopping is time-consuming

B．given prices help promote online sales

C．online businesses provide a lot of products

D．receiving offers makes online shoppers regretful小题3:The underlined word “taxed” in Para. 4 probably means______.

A．burdened

B．numbed

C．relieved

D．challenged小题4:The passage is mainly about______.

A．the big advantages of online shopping

B．the rapid development of online shopping

C．online shoppers’ preference for taking offers

D．online companies strategies to improve service

javabean 是java 的一种 ( ) 。

A．包

B．数组

C．类

D．变量