解方程：（4x+3）（9x-2）+7=（6x-1）2+3x-14．

如图所示，一质量为M=2kg的绝缘滑板静止于水平面上，它与水平面闻的动摩擦因数为=0.1，绝缘滑板上表面0点的左侧是光滑的，O点的右侧是粗糙的。有质量均为m="1" kg的小物块a、b分别静止地放于绝缘滑板的A点和O点，且A点与O点的间距L="0.5" m，小物块a、b均可视为质点，它们在O点右侧时与绝缘滑板间动摩擦因数均为弘- -整个装置所在空间存在着E=8×l03 N/C且方向水平向右的匀强电场，小物块a带有q=5×10^-4C的正电荷，b和滑板均不带电。若小物块在运动过程中电荷量始终不变，a与b相碰后粘合在一起且碰撞时间极短，小物块恰好能到达绝缘滑板的右端；最大静摩擦力在大小上等于滑动摩擦力，g取10m／s²。求：

（1）小物块a到达O点时的速度。 

（2）绝缘滑板的长度。

A device that stops drivers from falling asleep at the wheel is about to undergo testing at Department of Transport laboratories and could go on sale within 12 months.

The system, called Driver Alert, aims to reduce deadly road accidents by 20% - 40% that are caused by tiredness. Airline pilots can also use it to reduce the 30% of all pilot-error accidents that are related to fatigue.

Driver Alert is based on a computerized wristband. The device, worn by drivers or pilots, gives out a sound about every four minutes during a car journey. After each sound the driver must respond by squeezing the steering wheel. A sensor in the wristband detects this pressing action and measures the time between the sound the driver’s response.

Tiredness is directly related to a driver’s response time. Usually, a watchful driver would take about 400 milliseconds to respond, but once that falls to more than 500 milliseconds, it suggests that the driver is getting sleepy.

In such cases the device gives out more regular and louder sounds, showing that the driver should open a window or stop for a rest. If the driver’s response continues to slow down, the sounds become more frequent until a nonstop alarm warns that the driver must stop as soon as possible.

The device has been delivered to the department’s laboratories for testing. If these tests, scheduled for six months’ time, are successful, the makers will bring the product to market within about a year.

小题1:According to the text, Driver Alert ______.

A．aims to reduce tiredness-related accidents

B．has gone through testing at laboratories

C．aims to prevent drivers from sleeping

D．has been on sale for 12 months小题2:How should a driver respond to the sounds from Driver Alert?

A．By sounding a warning.

B．By touching the wristband.

C．By checking the driving time.

D．By pressing the steering wheel.小题3:We can learn form the text that the driver needs to stop for a break when his response time is ______.

A．about 400 milliseconds

B．below 500 milliseconds

C．over 500 milliseconds

D．about 4 minutes小题4:When the driver gets sleepy while driving, Driver Alert ______.

A．moves more regularly

B．stops working properly

C．opens the window for the driver

D．sounds more frequently and loudly

某投资者2003年准备投资购买股票，现有A、B两家公司可供选择，从A公司和B公司2002年12月31日的有关会计报表及补充资料中获知，2002年A公司发放的每股股利为5元，股票每股市价为40元;2002年B公司发放的每股股利为2元，股票每股市价为20元。预期A公司未来5年内股利固定，在此以后转为正常增长，增长率为6%；预期B公司股利将持续增长，年增长率为4%，假定目前无风险收益率为6%，市场上所有股票的平均收益率为10%，A公司股票的β系数为2，B公司股票的β系数为1.5。要求： (1)计算股票价值并与股票市价相比较，判断两公司股票是否应购买。 (2)若投资购买这两种股票各100股，利用CAPM计算该投资组合的预期收益率为多少

下列物质中不可能是食品发酵过程中发酵菌代谢产物的是（）

A、CO2

B、H2O

C、C2H5OH

D、O2