设备轻便、操作灵活，可以应用于短缝的焊接，特别是用于难以达到部位的焊接的焊接方法为( 发布时间：2018-01-10 01:54 │ 来源：www.tikuol.com 题型：单项选择题 问题： 设备轻便、操作灵活，可以应用于短缝的焊接，特别是用于难以达到部位的焊接的焊接方法为( )。A．手弧焊B．埋弧焊C．闪光焊D．电阻焊
题型：单项选择题 阅读理解。 Do you still get free plastic bags from the supermarkets? Things have changed. China has banned (禁止) free plastic bags at shops and supermarkets, and people have to pay for using plastic bags. The rule started on June 1st. It came because our country tried to make litter less. Making super-thin plastic bags has also been banned. The Chinese once used about 3,000,000,000 plastic shopping bags a day, and they have caused pollution of the environment. The bags have become a main cause of plastic pollution because they are easy to break and people throw them away here and there. So the Chinese people are encouraged to bring their own bags for shopping. What kind of shopping bag is the best to bring? Some students in chongqing have a good idea. They make their own shopping bags. They use old clothes to make cloth bags and send to their parents as presents.They also ask their parents and friends to use cloth bags instead of plastic ones. They think it is their duty to protect the environment. 1. People in China have to ________ now.[ ]A.Throw plastic bags here and there B.collect plastic bags in the street C.pay for using plastic bags at shops and supermarkets D.use free plastic bags at shops and supermarkets 2. China made this rule because plastic bags were bad for the _______[ ]A.environment B.litter C.shops D.supermarkets3. The Chinese people are encouraged to bring _______ for shopping.[ ]A.no bags B.free plastic bags C.their own bags D.super-thin plastic bags4. Some students in Chongqing _____________.[ ]A.ask their parents to make cloth bags B.make cloth bags themselves C.pick up plastic bags everywhere D.buy cloth bags for their parents 5. What is the main idea of this article?[ ]A. Making super-thin plastic bags has been banned in China. B. The bags have become a main cause of plastic pollution. C. Some students in Chongqing begin to make their own shopping bags. D. To protect the environment, free plastic bags have been banned in China. 查看答案
题型：单项选择题 计算：（1）(-2xy2)3+4xy2- 12x2y4；（2）(-1)-2+(12)-2-5÷(π-3)0；（3）用简便方法计算：20092-2010×2008；（4）[（x+y）（x-y）-（x-y）2+2y（x-y）]÷（4y）． 查看答案
题型：单项选择题 原发性甲亢是指（）A.甲状腺肿大的同时，出现功能亢进症状B.自主性甲状腺肿（高功能腺瘤）C.在结节性甲状腺肿的基础上并发功能亢进症状D.在甲状腺肿的基础上继发功能亢进症状E.先出现甲状腺肿大，后出现甲亢症状 查看答案