正常使用条件下，节能保温工程的最低保修期限为()年。A.2  B.3  C.4  D

公式G=mg中，g表示物体受到重力与质量之比，约等于9.8N/kg，在要求不精确的情况下，可取g等于10N/kg．

（1）为探究g的大小，小宇同学把不同质量的钩码挂在弹簧测力计上，分别读出它们的大小，记在下面表格中，再算出每次重力跟质量的比值．

质量m/kg	重力G/N	重力和质量的比值/（N•kg-1）
0.10	1.0	10
0.20	2.0	10
0.30	3.0	10

根据上述实验与数据，得出的结论是______．

（2）经科学家的精确测量，g值并不是固定不变的，在不同的地理位置，仍有差异．下表为各个不同城市的g值大小，观察分析表中提供的数据，回答下列问题．

地点	g值大小	地球纬度		地点	g值大小	地球纬度
赤道	9.780	0°		广州	9.788	23°06΄
武汉	9.794	30°33΄		上海	9.794	31°12΄
北京	9.801	39°56΄		纽约	9.803	40°41΄
莫斯科	9.816	55°45΄		北极	9.832	90°

①g值相同的城市是：______．

②g值相差最大的两地是：______．

③试猜想g值变化的原因可能是：______．

基因芯片的实质是一种（）

A.高密度的单克隆抗体阵列

B.高密度的多肽阵列

C.高密度的核酸阵列

D.高密度的寡核苷酸阵列

E.高密度的蛋白阵列

阅读理解。

      You are watching a film in which two men are having a fight. They hit one another hard. At the start they

only fight with their fists. But soon they begin hitting one another over the heads with chairs. And so it goes on

until one of the men crashes through a window and falls thirty feet to the ground below. He is dead!Of course

he isn't really dead. With any luck he isn't even hurt. Why? Because the men who fall out of high windows or

jump from fast moving trains are professionals. They do this for a living. These men are called stuntmen. That

is to say, they perform tricks. There are two sides to their work. They actually do most of the things you see

on the screen. For example, they fall from a high building. However, they do not fall on to hard ground but on

to empty cardboard boxes covered with a mattress (床垫). Again, when they hit one another with chairs, the

chairs are made of soft wood and when they crash through windows, the glass is made of sugar! But although

their work depends on trick of this sort, it also requires a high degree of skill and training. Often a stuntman's

success depends on careful timing. For example, when he is "blown up" in a battle scene, he has to jump out

of the way of the explosion just at the right moment.

       Naturally stuntmen are well paid for their work, but they lead dangerous lives. They often get seriously

injured, and sometimes killed. A Norwegian stuntman, for example, skied over the edge of a cliff (悬崖) a

thousand feet high. His parachute (降落伞) failed to open, and he was killed. In spite of all the risks, this is no

longer a profession for men only. Men no longer dress up as women when actresses have to perform some

dangerous action. For nowadays there are stuntgirls tool.

1. Stuntmen are those who ______. [ ]

A. often dress up as actors

B. prefer to lead dangerous lives

C. often perform seemingly dangerous actions

D. often fight each other for their lives

2. Stuntmen earn their living by ______. [ ]

A. playing their dirty tricks

B. selling their special skills

C. jumping out of high windows

D. jumping from fast moving trains

3. When a stuntman falls from a high building, ______.[ ]

A. he needs little protection

B. he will be covered with a mattress

C. his life is unprotected

D. his safety is generally all right

4. Which of the following is the main factor (因素) of a successful performance? [ ]

A. Strength.

B. Exactness.

C. Speed.

D. Carefulness.

5. What can be inferred from the author' s example of the Norwegian stuntman? [ ]

A. Sometimes an accident can occur to a stuntman.

B. The percentage of serious accidents is high.

C. Parachutes must be of good quality.

D. The cliff is too high.

发生认识论的提出者是( )

A．阿恩海姆
B．里普斯
C．布洛
D．皮亚杰

如果把谈恋爱这三个词代表人生亲密的三个阶段，那么高中阶段及以前谈是重要的，大学阶段爱很重要。