搜题请搜索小程序“爱下问搜题”
问题 单项选择题

已知某双代号网络计划中，该工作ES＝4 d、EF＝6 d、LS＝7 d，LF＝9 d，则该工作的总时差为( )。

A．1 d

B．2 d

C．3 d

D．5 d

答案

参考答案：C

选择题

设阿伏加德罗常数的值为，则下列说法正确的是    (    )

A．标准状况下，22.4 L乙烯含有的共用电子对数为2

B．常温下，含有1 mol NaHSO4溶液中的阳离子数为

C．通常状况下，1 mol NO和0.5 molO2在密闭容器中混合，生成NO2分子数为

D．制取漂白粉时，标准状况下22.4 LCl2参加反应，转移电子数为
查看答案
单项选择题

It’s all annual back-to-school routine. One morning you wave goodbye, and that (1) evening you’re burning the late-night oil in sympathy. In the race to improve educational standards, (2) are throwing the books at kids. (3) elementary school students are complaining of homework (4) What’s a well-meaning parent to do.As hard as (5) may he, sit back and chill, experts advise. Though you’ve got to get them to do it, (6) helping too much, or even examining (7) too carefully, you may keep them (8) doing it by themselves. "I wouldn’t advise a parent to check every (9) assignment," says psychologist John Rosemond, author of Ending the Tough Homework. "There’s a (10) of appreciation for trial and error. Let your children (11) the grade they deserve. " Many experts believe parents should gently look over the work of younger children and ask them to rethink their (12) . But "you don’t want them to feel it has to be (13) ," she says.

That’s not to say parents should (14) homework-first, they should monitor how much homework their kids (15) . Thirty minutes a day in the early elementary years and an hour in (16) four, five, and six is standard, says Rosemond. For junior-high students it should be " (17) more than an hour and a half," and two for high school students. If your child (18) has more homework than this, you may want to check (19) other parents and then talk to the teacher about (20) assignments.

3（）

A.Also

B.Even

C.Then

D.However
查看答案