8AS-12.5型压缩机,其卸载机构的顶杆过长,将造成不能卸载的故障。

题型:判断题

问题:

8AS-12.5型压缩机,其卸载机构的顶杆过长,将造成不能卸载的故障。

考点:制冷工考试制冷原理与制冷系统制冷原理与制冷系统题库
题型:判断题

Do you have an umbrella? Someone invented the umbrella about 4,000 years ago. People used umbrellas in Egypt, Assyria, Greece, and China in ancient times. We use our umbrella for protection from the rain. However, people first used umbrellas for protection from the sun. People in China were the first ones to use their umbrellas for rain. They put wax(蜡纸) on paper umbrellas.

European women used umbrellas before European men used them. Jonas Hanway was the first man to carry one in England. He made umbrellas popular for men and women. Some people called the umbrella a Hanway because of him.

We make umbrellas from many different things. The first ones were wood and cloth. Now many are plastic(塑料). Today umbrellas are easy to carry. They fold up into a small package(包). The umbrella is a great invention. Don’t forget yours the next time when it rains.

根据文章内容判断正误,正确的写“A”,错误的写“B”。

小题1:The umbrella was invented about 2,000 years ago.

小题2:The first umbrellas were used for protection from sun.

小题3:People in Europe were the first ones to use their umbrellas for rain.

小题4:Some people called the umbrella a Hanway because he made umbrellas popular for people.

小题5:The first umbrellas were made from plastic.

题型:判断题

(10分)某化学兴趣小组为了测定某石灰石样品中碳酸钙的质量分数,取用2.0 g石灰石样品,把25.0g质量分数为10%的稀盐酸分五次加入样品中(样品中的杂质既不与盐酸反应,也不溶解于水),每次充分反应后都经过滤、干燥、称量,得实验数据如下:

实验次数12345
稀盐酸的累计加入量5.0g10.0g15.0g20.0g25.0 g
剩余固体的质量1.5g1.0g0.5g0.3g0.3g
请计算:

(1)2.0g石灰石样品中碳酸钙的质量为     ,石灰石中碳酸钙的质量分数为      。

(2)请你继续计算反应生成溶液中氯化钙的质量分数(计算过程和结果均保留一位小数)

题型:判断题

已知碳酸钙在高温煅烧时生成生石灰(氧化钙)和二氧化碳气体,若要制得11.2t的生石灰,需要煅烧多少碳酸钙?

题型:判断题

利用宽展量计算可以根据给定的()来确定轧制后产品的尺寸。

A.坯料尺寸

B.压下量

C.轧制压力

D.前滑量

题型:判断题

脊柱与脊椎骨

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