单项选择题

为限制频率降低，切除抽水蓄能机组和启动备用电源的动作频率可为（）左右。

A.49.5Hz
B.49.2Hz
C.49.0Hz
D.48.5Hz

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单项选择题

W：I’m pretty confident the company where I worked the past two summers will hire me full time after graduation.
M：Well，just in case that it doesn’t work out.Career service is having a workshop on campus next Thursday on applying for a job.They had one here last year，and I know a lot of people found it helpful.
Q：What does the man suggest the woman do？（）

A．Speak to his previous employer.
B．Get a job working on campus.
C．Attend the career services workshop.
D．Get a job application from him.

单项选择题

一般将城市人口的年龄分为:
①托儿组(0~2岁)、
②幼儿组(3~6岁)、
③小学组(7~11岁或7~12岁)、
④中学组(12~16岁或13~18岁)、
⑤成年组(男:17~65岁,女17或19~60岁)、
⑥老年组(男:61岁以上,女56岁以上)、
⑦托儿组(0~3岁)、
⑧幼儿组(4~6岁)、
⑨成年组(男:17~60岁,女:17或19~55岁)。其中划分正确的是( )。

A.①②③④⑤⑥
B．⑦②③④⑤⑥
C．⑦⑧③④⑨⑥
D．⑦⑧③④⑤⑥