问题 选择题

给出下列四个命题,其中正确的一个是(  )

A.从匀速传递的产品生产流水线上,质检员每20分钟从中抽取一件产品进行某项指标检测,这样的抽样是分层抽样

B.在线性回归模型中,相关指数R2=0.70,说明预报变量对解释变量的贡献率为70%

C.相关指数R2用来刻画回归效果,R2越小,则残差平方和越大,模型的拟合效果越好

D.随机误差e是衡量预报精确度的一个量

答案

从匀速传递的产品生产流水线上,

质检员每20分钟从中抽取一件产品进行某项指标检测,

这样的抽样是系统抽样,故A不正确,

用相关系数r可以衡量两个变量之间的相关关系的强弱,根据“相关指数R2=0.70”并不能说明预报变量对解释变量的贡献率是70%,故B不正确;

用相关指数R2来刻画回归效果,R2越大,说明模型的拟合效果越好,C不正确,

随机误差e是衡量预报精确度的一个量,它满足E(e)=0.D正确,

故选D.

阅读理解

It’s reported that a company called MicroCHIPS has developed a wirelessly controlled device(装置). The device is put under the skin and can supply a drug directly into the patient’s body. People give the name “microchips” to it.

Microchips bring good news to patients with long-term( 长期的) illnesses, for example, Osteoporosis( 骨质疏松症). People with Osteoporosis have to get daily injections( 注射) of medicine. One type of treatment requires injections for two years. Many patients stop taking the medicine because of the pain and stress of the infections. However, microchips can deal with it. Doctors will program the device before putting it under the skin, and the device has the ability to release(释放) a dose (剂量) at a given time, every single day. One microchip can hold a full year’s worth of medicine.

Microchips may one day free (使…… 摆脱)people from having to remember to take their medicine, or get injections. The device may also be useful in treating other long-term diseases, including heart disease, cancer and even AIDS.

小题1:What is the passage mainly about?

A.It introduces the company MicroCHIPS.

B.It introduces a new wirelessly controlled device called “ microchips”.

C.It introduces some common long-tern diseases.

D.It’s about how the device called“microchips”works.小题2:According to the passage, why do many patients stop getting injections?

A.Because of the pain and stress of the injections.

B.Because they are too lazy.

C.Because they like taking pills(药丸).

D.Because they are waiting for the new device.小题3:According to how the device works, which of the following is the correct order?

① Put the device under the skin.

② The device releases a dose at a given time.

③ Doctors program it.

A.①②③

B.②③①

C.③①②

D.③②①

单项选择题