Speed regulation system using cascade control method with thyristor is a low-cost system, but the classic system has some shortages, such as low power factor, serious harmonic pollution and etc.

晶闸管串级调速系统是一种廉价、简易的调速系统，但是传统串调系统存在着诸如功率因数低、谐波污染严重等弊端。

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As we have seen, control of pollution via nuisance actions and direct regulation is not without its problems.

我们已经清楚妨害行为和直接管制污染并非是没有问题的。

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Under the Water Pollution Control (Sewerage) Regulation, the EPD requires house or development owners to connect their sewage to the public sewers.

环保署根据《水污染管制(排污设备)规例》，规定物业业主把污水接驳至公共污水渠。

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These companies, and some unions that see the rules as a potential economic catalyst, say that the industry has had years to prepare for tougher regulation and that the rules will generate jobs for workers who make, install or operate pollution control equipment.

WSJ: EPA Tangles With New Critic: Labor