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有水塔和无水塔管网，二级泵站的扬程如何计算？

答案

参考答案：

有水塔时，按供水量曲线确定；无水塔时，按最高日用水量确定。

单项选择题

第2篇 Tightened Visa Regulations


According to South Korea’s new visa regulations, native speakers of English who intend to teach English in South Korea will be required to undergo criminal record checks, medical and drug tests, provide sealed academic transcripts and have their university diplomas inspected, The Korea Times has reported. The tightened regulations will affect an estimated 17,000 foreigners that hold E-2 visas specifically for foreign language teachers.
The most controversial requirement is that English teachers residing outside South Korea will have to have an interview at a South Korean embassy before taking up their teaching posts. For applicants living in remote areas in Canada, Australia or the US, this is an additional travel burden. Meanwhile, foreign teachers currently living in South Korea must leave the country after their one-year contracts end and renew their visas at a South Korean embassy in their home country or third country. Before the changes, they could renew their visas by visiting a neighboring country and return without additional documentation.
The visa changes are a reaction to public concern about the suitability of some foreign teachers. A report from the South Korean Ministry of Education and Human Resources Development shows between 2001 and August of this year, 1,481 foreign language teachers have been caught for a range of offenses including forged degrees, visa violations and general lawbreaking.
But the changes are likely to slow up the supply of teachers to South Korea’s English language education sector. According to Michael Dully, manager of a teacher placement service in South Korea, applicants have to spend a few hundred dollars and several months on getting affidavits for documents. "South Korea has put up too many hoops to jump through. " he said, adding that foreigners would seek work elsewhere. Most foreigners wonder if the experience of working in South Korea will be worth the burden of the paper work and increasing restrictions. "I don’t think (South) Korea has thought this through. " said Scott McInnis, a Canadian teacher based in Incheon near Seoul. "This is a reactionary move by the government that will have p implications for the EFL community. "
As part of efforts to ease the discontent, the South Korean Ministry of Justice has granted a three-month grace period for current E-2 visa holders to prepare the necessary documents.

Before the change of visas regulation, foreign teachers living in South Korean can ______ to teach again.

A．have an interview again at a South Korean embassy

B．return to their own country to renew their visas

C．visit a neighboring country if they wanted to renew their visas

D．produce additional documentation to renew their visas
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填空题

下表是关于风力提水机组的材料：产品名称：FD4型风力提水机组

风轮直径：4m起动风速：4m/s额定转速：360r/min提 水 量：15m3/h
叶 片 数：18工作风速：4～17m/s额定风速：8m/s提水高度：9m
请根据上述数据计算，这台机组正常工作时获得的风能功率为______W，提水功率为______W．（设吹到整个风轮圆面积上的空气减速为零，不考虑水的动能变化．空气密度ρ0=1.29kg/m3，g=10m/s2．）
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