简述需要的定义及特征。

It is important to do with the rubbish in cities. Rubbish must be      1.____________

treated properly. Thus, it may cause a lot of prob¬lems. It may pollute     2.____________

the air and water. When people breathe the polluted air or drink polluted3.____________

water, we may get ill. Our city has begun to pay attention to the roblem.  4.____________

As far as I know, some rubbish is sorted and sent to different facto¬ry.      5.____________

Rubbish, such as old newspapers and glass, are recycled. Some harmful   6.____________

rubbish is sent to a certain place and buried. Waste air is cleaned after it  7.____________

goes into the air. Waste water is treated before it poured into rivers. To   8.____________

protect from the environment, the government has passed laws to           9.____________

prevent people from throwing rubbish everywhere. We should do our        10.___________

best to take good care of the environment and fight against pollution.

对口焊接时，若焊接处缝隙过大，不允许强力对口，应另加一段短管，其长度不小于（）。

A、100mm

B、80mm

C、60mm

D、40mm

金刚石钻进的特点叙述错误的是（）。

A、钻进效率高

B、应用范围小

C、钻孔质量好

D、装备轻，劳动强度低

紧急缺陷的消除时间或立即采取限制其继续发展的临时措施的时间不超过（）小时。

A.12

B.24

C.48

D.36

男性，32岁，既往健康，有烟酒嗜好。1年前发现左上肢"红线"，伴肿硬，压痛。5个月前感觉右下肢凉、怕冷，麻木，行走200米出现小腿疼痛。近1个月症状加重，出现夜间疼痛。查体：右下肢发绀，皮温凉，右股动脉弹性好，足背胫后动脉搏动未触及。诊断应考虑为（）

A.右下肢血栓性浅静脉炎

B.下肢静脉曲张

C.动脉硬化闭塞症

D.血栓闭塞性脉管炎

E.下肢深静脉血栓