一个数的平方一定是[ ] A.正数 B.负数 C.非正数 D.非负数

题型:选择题

问题:

一个数的平方一定是[ ]

A.正数

B.负数

C.非正数

D.非负数

考点:有理数的乘方
题型:选择题

弹簧振子以O点为平衡位置在B、C两点之间做简谐运动.B、C相距20cm.某时刻振子处于B点.经过0.5s,振子首次到达C点.求:

(1)振动的周期;

(2)振子在5s内通过的路程及偏离平衡位置的位移大小.

题型:选择题

直角三角形中,一个锐角是37 °,另一个锐角是(    )。

题型:选择题
从匀速直线运动的速度公式V=S/t中可知(  )

A.速度与时间成反比

B.速度与路程成正比

C.速度不变时,路程与时间成正比

D.以上说法都不对

题型:选择题

China in the 21st century is making great progress in space technology. In 2003, the country sent up the manned spacecraft Shenzhou-V. Four years later, Chang’e-I went into orbit (轨道) around the moon. In 2008 a Chinese man did the country’s first spacewalk.

These achievements would have been unthinkable without the contribution of Qian Xuesen, a key scientist on space programs and rocketry (火箭技术) of the People’s Republic of China. This pioneering scientist passed away in Beijing on October 31 in 2009 at the age of 98.

Once called “the father of our space industry”, Qian began working on China’s missile and space technology in 1956, when China had little technology. When asked by General Chen Geng whether the Chinese could develop their own missiles, Qian said Chinese could do anything that foreigners could.

His research helped lead to the explosion of China’s first atomic bomb (原子弹) in1964, as well as to its first man-made satellite in 1970 and its first manned spacecraft in 2003.

Qian was born in Shanghai. He graduated from Shanghai Jiaotong University in 1934.Then he studied in the US at the Massachusetts Institute of Technology and later at the California Institute of Technology. During World WarⅡ, Qian’s research contributed to the development of rocket technology that the US military (军队) began using in the 1940s. He was once prevented from leaving the country because it was decided that he knew too much about certain military matters. It was not until in 1955 that Qian returned to China with the help of the late premier Zhou Enlai.

“I plan to do my best to help the Chinese build a nation where they can live with dignity (尊严) and happiness, ” Qian told reporters before sailing for China in 1955. The great scientist devoted all his life to keeping the promise.

小题1: What is the article mainly about?

A.It gives a short history of Chinese missile and space programs.

B.It is about how Qian contributed to the Chinese space program.

C.It lists important events that Qian experienced.

D.It is a brief introduction to Qian, a famous Chinese scientist.小题2:. Which statement about Qian is TRUE?

A.He was born in China and brought up in America.

B.He went to America for further study after graduation from university.

C.He returned to his hometown right after finishing his education.

D.He had worked on missiles in the US military before coming back to China.小题3:Qian was personally involved in many historic events in China EXCEPT       .

A.the first spacewalk

B.the first man-made satellite

C.the development of missiles

D.the explosion of an atomic bomb小题4: From the article, we can conclude that       .

A.the US military had hoped to take full advantage of Qian’s talent

B.Qian had an important position in the US military in the 1940s

C.when World War broke out, Qian was studying at Shanghai Jiaotong University

D.it was not easy to get Qian back from the US

题型:选择题

同一药物制成的口服制剂,药物吸收速度最快的是()。

A.散剂

B.片剂

C.胶囊

D.溶液

E.混悬剂

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