4/17， 7/13， 10/9， ( )。A．13/6 B．13/5 C．14/_爱下问搜题

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问题单项选择题

4/17， 7/13， 10/9， ( )。

A．13/6

B．13/5

C．14/5

D．7/3

答案

参考答案：B

解析：分子是以4为首项，3为公差的数列，分母是以17为首项，-4为公差的数列。

名词解释

吞噬体

阅读理解

_{阅读理解。
       1   If not, and if right now you're not focusing on this article, your time might be better spent on a short
nap (小睡) to boost (促进) your focus and productivity (效率).
     That's what the National Sleep Foundation says, and it's a message that health education professionals at
the University of California at Davis (a city of California, America) have been spreading to their students.
     "We're familiar with the benefits of sleep," said Amelia, a student in sleep and stress at the UC Davis health
center.   2 For students, the benefits of increased productivity and focus will help their scores-even though
there is no data to back that up.
     However, research has repeatedly shown that when students have 7-9 hours of sleep, 20-30 minute naps
do offer these benefits,   3
     So Jason B. Spitzer, a health educator, believes encouraging students to take naps to improve their state of
mind-not to mention stay awake during classes - is very important.
     Health educators discovered that while 33 percent of Davis students didn't nap at all, three-quarters of those who did nap did so for too long-more than 30 minutes. That told the educators that a napping campaign would
have to focus on two different populations:   4 Health educators hand out "nap tools"; they include earplugs
(耳塞), an eye mask and a tip card with directions to more messages online. They advertise in the student
newspaper introducing napping tips and benefits, and they team with the student government to spread the
word on napping during National Sleep Awareness Week.
       5 "We want to improve their napping and their sleep quality." Spitzer said.
A. Did you get a complete and restful night's sleep last night?
B. non-nappers and long nappers.
C. The Davis campaign is still changing every year.
D."We're not familiar with the positive effects of napping."
E. We should try our best to nap when it is necessary.
F. Napping is very important to us.
G. particularly when taken between the hours of 10 to 11 am or 2 to 4 pm.}