纵波和横波在古登堡界面处发生的显著变化是 ( ) A．波速都降低为零 B．波速都

病原携带者可分为以下哪几种（）。

A.长期病原携带者

B.潜伏期病原携带者

C.恢复期病原携带者

D.终生病原携带者

E.健康病原携带者

如图所示，妈妈买了一辆电动车，回家后却发现一个难题：车库里只有一盏灯，但没有充电用的插座．爸爸打开灯的开关盒，看到里面有两个接线柱，于是他从这两个接线柱上引出两根导线，接上一个插座．接好后插上充电器，却发现电灯亮了，但亮度明显偏暗，造成这一现象的原因是由于连接错误而导致充电器与电灯 ________ 联；这时充电器 ________ （能/不能）正常充电，理由是__________．

甲状腺功能亢进患者的大便次数多，是因为（）

A.肠蠕动过快

B.甲状腺素过少

C.基础代谢率高

D.肠痉挛

E.内分泌紊乱

清洁规程制定的依据及其内容是什么？

Wherever people have been, they have left waste behind, which can cause all sorts of problems. Waste often stinks, attracts vermin and creates eyesores. More seriously, it can release harmful chemicals into the soil and water when dumped, or into the air when burned. And then there are some really nasty forms of industrial waste, such as spent nuclear fuel, for which no universally accepted disposal methods’ have thus far been developed.

Yet many also see waste as an opportunity. Getting rid of it all has become a huge global business. Rich countries spend some $120 billion a year disposing of their municipal waste alone and another $150 billion on industrial waste. The amount of waste that countries produce tends to grow in tandem with their economies, and especially with the rate of urbanization. So waste firms see a rich future in places such as China, India and Brazil, which at present spend only about $5 billion a year collecting and treating their municipal waste.

Waste also presents an opportunity in a grander sense: as a potential resource. Much of it is already burned to generate energy. Clever new technologies to turn it into fertiliser or chemicals or fuel are being developed all the time. Visionaries see a world without waste, with rubbish being routinely recycled.

Until last summer such views were spreading quickly. But since then plummeting prices for virgin paper, plastic and fuels, and hence also for the waste that substitutes for them, have put an end to such visions. Many of the recycling firms that had argued rubbish was on the way out now say that unless they are given financial help, they themselves will disappear.

Subsidies are a bad idea. Governments have a role to play in the business of waste management, but it is a regulatory and supervisory one. They should oblige people who create waste to clean up after themselves and ideally ensure that the price of any product reflects the cost of disposing of it safely. That would help to signal which items are hardest to get rid of, giving consumers an incentive to buy goods that create less waste in the first place.

That may sound simple enough, but governments seldom get the rules right. In poorer countries they often have no rules at all, or if they have them they fail to enforce them. In rich countries they are often inconsistent: too strict about some sorts of waste and worryingly lax about others. They are also prone to imposing arbitrary targets and taxes. California, for example, wants to recycle all its trash not because it necessarily makes environmental or economic sense but because the goal of “zero waste” sounds politically attractive.

Waste firms expect a great development in China, India and Brazil because（）

A. those economies have a large amount of waste to be treated

B. those economies develop fast but spend little on waste business

C. those economies welcome waste firms to run business there

D. those economies pay more attention to environmental protection