某人沿着半径为R的水平圆周跑道跑了1.5圈时，他的（ ） A．路程和位移的大小均

如图所示，小球A系在细线的一端，线的另一端固定在O点，O点到水平面的距离为h。物块B质量是小球的5倍，置于粗糙的水平面上且位于O点正下方，物块与水平面间的动摩擦因数为μ。现拉动小球使线水平伸直，小球由静止开始释放，运动到最低点时与物块发生正碰（碰撞时间极短），反弹后上升至最高点时到水平面的距离为。小球与物块均视为质点，不计空气阻力，重力加速度为g，求物块在水平面上滑行的时间t。

ab=ba表示乘法交换律．______（判断对错）

通常情况下夏普指数以（）数据进行计算。

A.日

B.月

C.季度

D.年或年化

白血病细胞中有Auers小体对鉴别白血病细胞类型有重要作用，下列哪项是错误的（）

A.M1的原粒细胞可见Auers小体

B.M3的早幼粒细胞的Auers小体短而粗，数量多

C.M6的原粒细胞也可见Auers小体

D.L3的原始细胞中Auers小体长而细

E.M7的原始细胞是无Auers小体

阅读理解.

     She is widely seen as proof that good looks can lastforever. But,at over 500 years of age,

time is catching up with the Mona Lisa.

     The health of the famous picture,painted by LeonardoDa Vinci(莱昂纳多·达·芬奇)in

1505,is getting worse bythe year,according to the Louvre Museum(卢浮宫博物馆)where

it is housed. "The thin, woodenpanel on which the Mona Lisa is paintedin oil has changed

shape since expertschecked it two years ago. "the museumsaid. Visitors have noticed the

changesbut repairing the world's most famous                                

  painting is not easy. Experts are not sure about the materialsthe

Italian artist used and their currentc现在的) chemicalstate.

     Nearly 6 million people go to see the Mona Lisa everyyear,and many are attracted by the

mystery of her smile. "It is very interesting that when you're not looking at her,sheseems to be

smiling, and then you look at her and shestops." said Professor Margaret Livingstone of

HarvardUniversity. "It's because direct visionc视觉) is excellent atpicking up details,but tess

suited to look at shadows. DaVinci painted the smile in shadows. "

     However,the actual history of the Mona Lisa is just asmysterious as the smile. Da Vinci

 himself loved it so muchthat he always carried it with him, until it was eventuallysold to

France's King Francis I in 1519.

      In 1911,the painting was stolen from the Louvre by aformer employee, who took it out

of the museum hiddenunder his coat. He said he planned to return it to Italy. The painting

was sent back to France two years later.

     During World Warll ,French hid the painting in smalltowns to keep it out of the hands

of German forces.

     Like many old ladies, the Mona Lisa has someinteresting stories to tell.

1. The underlined sentence in the first paragraph means the Mona Lisa .

A. is losing its value

B.is being damaged after so many years

C.is getting more valuable with years passing

D. will rot away   

2. The smile of the Mona Lisa can only be seen_,

A. by indirect vision

B. at a distance

C. by direct vision

D. in shadows 

3. Which of the following is TRUE about Mona I.isa?  

A.It was once taken away and hidden up by German forces.

B. Its painter himself loved it greatly and always kept it in a shade.

C. Mona Lisa stops smiling when you look at her wantingto see her smiles.

D. King FrancisIbought it and then returned it to Italy.

4. It may add to the difficulty in repairing the painting that ~

A.experts haven' t noticed changes in its shape asvisitors do

B. it is likely to be stolen again when it's under repair

C.it is uncertain which country,Italy or France,shouldtake charge

D.experts aren't sure about the materials and the chemical state of its oil paint