下列药品中，数量点收时必须有两人以上同时在场，逐箱验点到最小包装的是（） A.贵重药

向明矾溶液中逐渐滴加Ba(OH)₂溶液，符合要求的离子方程式为

A．加入过量的Ba(OH)₂溶液时：2Al³⁺+3SO₄^2-+3Ba²⁺+6OH^—→ 2Al(OH)₃↓+3BaSO₄↓

B．溶液恰好呈中性时：2Al³⁺+3SO₄^2-+3Ba²⁺+6OH^—→ 2Al(OH)₃↓+3BaSO₄↓

C．SO₄^2－离子恰好完全沉淀时：Al³⁺+2SO₄^2-+2Ba²⁺+4OH^—→ AlO₂^－+2BaSO₄↓+2H₂O

D．明矾与Ba(OH)₂按物质的量比1∶1反应时：Al³⁺+SO₄^2-+Ba²⁺+3OH^—→ Al(OH)₃↓+BaSO₄↓

试述牵张反射的概念、产生机制及类型。

In 1993, New York State ordered stores to charge a deposit on beverage (饮料) containers. Within a year, consumers had returned millions of aluminum cans and glass and plastic bottles. Plenty of companies were eager to accept the aluminum and glass as raw materials for new products, but because few could figure out what to do with the plastic, much of it wound up buried in landfills (垃圾填埋场). The problem was not limited to New York. Unfortunately, there were too few uses for second-hand plastic.

Today, one out of five plastic soda bottles is recycled (回收利用) in the United States. The reason for the change is that now there are dozens of companies across the country buying discarded plastic soda bottles and turning them into fence posts, paint brushes, etc.

As the New York experience shows, recycling involves more than simply separating valuable materials from the rest of the rubbish. A discard remains a discard until somebody figures out how to give it a second life—and until economic arrangements exist to give that second life value. Without adequate markets to absorb materials collected for recycling, throwaways actually depress prices for used materials.

Shrinking landfill space, and rising costs for burying and burning rubbish are forcing local governments to look more closely at recycling. In many areas, the East Coast especially, recycling is already the least expensive waste-management option. For every ton of waste recycled, a city avoids paying for its disposal, which, in parts of New York, amounts to savings of more than $100 per ton. Recycling also stimulates the local economy by creating jobs and trims the pollution control and energy costs of industries that make recycled products by giving them a more refined raw material.

Recycling has become the first choice for the disposal of rubbish because ().

A. local governments find it easy to manage

B. recycling has great appeal for the jobless

C. recycling causes little pollution

D. other methods are more expensive

毛坯的选择包括（）和（）的选择。

具有补益作用的润肠药是（）

A.肉苁蓉

B.锁阳

C.杏仁

D.菟丝子

E.牛蒡子