要改变三相鼠笼式导师步电动机的旋转方向，只需把（）就可实现。

列各项中，属于现金流量表“经营活动产生的现金流量”的有（）。

A．支付的借款利息

B．销售商品收到的现金

C．代扣代缴的职工个人所得税

D．支付的行政人员因公出差的差旅费

A study finds that not enough morning light causes teenagers not to get enough sleep at night. “As teenagers spend more time indoors, they miss necessary morning light. Day light is needed to keep the balance of the body’s 24-hour biological system (生物系统), which regulates (调节) body temperature and sleep styles,” reports Dr. Mariana Figueiro. “These teenagers who receive little morning light are going to bed later, getting less sleep and doing badly in tests. They are more likely to fail in their exams.”

In the study, Dr. Figueiro asked 11 students in Grade 8 to wear special glasses to prevent blue morning light from reaching their eyes. At the end of the 5-day study she found that they fell asleep 30 minutes later than usual.

Throughout her research, Dr. Figueiro has been very worried about teenagers going to bed too late. The problem is that today’s schools require teenagers to be in school very early in the morning. These students are likely to miss the morning light because they often go to school before the sun is up or as it’s just rising.

Furthermore (此外), the schools are not likely to provide enough electric light to keep the balance of this biological system. Our biological system is much more sensitive (敏感的) to blue light. Therefore, having lots of light in the classroom does not make sure that there is enough light to keep our biological system balanced.

小题1:Which of the following is the result of the study?

A．Blue light in the morning harms the biological system.

B．Not enough morning light keeps teenagers sleep less.

C．Not getting more light in the morning make teenagers happy.

D．Not enough sleep makes teenagers fail in tests.小题2:We know from the passage that morning light __________.

A．has the same effects as afternoon light

B．may change studying habits of teenagers

C．is important to children’s biological system

D．has no effect on students’ tests小题3:What’s the problem of the students according to the study?

A．There are not enough electric lights in the classroom.

B．Being in school early affects their study habits.

C．They have to go to bed very early to have enough sleep.

D．They go to school too early to get enough morning light.

氮气压缩机流量调节利用（）控制。

A.余隙

B.电机转速

C.吸入阀开度

D.排出阀开度

关于系统垂直失调，以下说法错误的是（）

A.机械循环垂直双管系统垂直失调的原因，是由于通过各层的循环作用压力不同

B.重力循环垂直单管系统垂直失调的原因，是由于通过各层的循环作用压力不同

C.重力循环垂直双管系统垂直失调的原因，是由于通过各层的循环作用压力不同

D.楼层数越多，垂直失调越严重

安全管理中采用的“职位轮换”或者“强制休假”办法是为了发现特定的岗位人员是否存在违规操作行为，属于（）控制措施。

A、管理

B、检测

C、响应

D、运行