二尖瓣狭窄不会引起（） A.右心房增大 B.右心室增大 C.左心房增大

下列加点词的活用分类正确的一项是（   ）

①六王毕，四海一  ②愿陛下矜悯愚诚  ③腾跃而上         ④日益骄固    ⑤猥以微贱  

⑥鼎铛玉石  ⑦齐谐者，志怪者也     ⑧襟三江而带五湖   ⑨未云何龙    ⑩此亦飞之至也  

⑾屈贾谊于长沙  ⑿秦人不暇自哀，而后人哀之

A．①/②⑤⑦/③⑥⑨/④/⑧/⑩/⑾/⑿

B．①/②⑤⑦/③⑨⑿/④/⑥⑧/⑩/⑾

C．①/⑤⑦/③⑨/④/⑥⑧/②⑩/⑾/⑿

D．①/②⑤⑦/⑥⑨/③④/⑧/⑩/⑾/⑿

若4x²-12xy+m²是一个完全平方式，则m的值为多少？

Mulch is a protective cover of material that is spread on top of soil.It is usually made out of organic material, like crop waste.Farmers may keep the remains of maize or other crops on top of the soil.This creates mulch on the soil surface.The plant remains help protect the soil against wind and water damage.Mulching is one of the best things people can do for their plants.It also helps keep the soil from getting dry, and reduces the need for watering plants.It also limits temperature changes in the soil.And it stops unwanted plants, or weeds，from growing.

Organic mulch improves the condition of soil.As the mulch breaks down, it provides material which keeps the soil from getting hard.This improves the growth of roots and increases the movement of water through the soil.It also improves the ability of the soil to hold water. Organic mulch contains nutrients for plants.It also provides a good environment for earthworms and other helpful organisms in the soil.

It is easy to find organic mulch materials.Cut­up leaves and small pieces of tree bark can be used.Grass cuttings are also a good mulch for plants. Mulch from newspapers works well in controlling weeds.

The best time to add mulch depends on your goal.Mulch provides a thick barrier between the soil and the air.This helps to reduce temperature changes in the soil. As a result，mulched soil will be cooler than other soil in the summer.In winter, the mulched soil may not freeze as deeply as other soil.The best time is after the ground has frozen, but before the coldest weather arrives.Spreading mulch before the ground has frozen may attract small animals searching for a warm place to spend the winter.Delaying the spreading should prevent this problem.The animals will probably find another place to live.

小题1:The author tells us the following EXCEPT________.

A．what mulch is and its benefits

B．the best time to add mulch

C．what can be mulched on the soil surface

D．the bad effects of mulch小题2:The following can be used as organic materials to make mulch EXCEPT________.

A．tree barks

B．cut­up leaves

C．grass cuttings

D．plastic小题3:Which of the following is the benefit of mulch?

A．Protecting the soil against wind and water damage.

B．Keeping the soil wet and reducing the need for watering plants.

C．Reducing temperature changes in the soil and stopping unwanted weeds

growing.

D．All of the above.小题4:The main idea of Paragraph 2 is that organic mulch can________.

A．improve the condition of soil

B．improve the ability of the soil to hold water

C．provide a good environment for earthworms

D．improve the growth of roots and increase the movement of water through thesoil

小题5:From the last paragraph, we know ________.

A．the best time to add mulch is in spring and summer

B．the best time to add mulch is after the coldest weather arrives

C．the best time to add mulch depends on weather

D．choosing the best time to add mulch can avoid attracting small animals

对无机材料的性质均不利的因素为( )

A．材料吸水

B．增加孔隙数量

C．细化晶粒

D．均匀分布各组成

结构化设计方法的设计原则是（）。

A.模块间共用的信息（如参数等）尽量少。

B.模块间传送的参数作数据用。

C.使每个模块执行一个功能。

D.每个模块用过程语句（或函数方式等）调用其他模块。