问题 问答题 论述题

可编程序控制器程序设计有哪些步骤?

答案

参考答案:

可编程序控制器程序设计的步骤为:

①详细了解生产工艺和设备对控制系统的要求;

②将所有输入信号(按钮、行程开关、速度及时间等传感器),输出信号(接触器、电磁阀、信号灯等)及其它信号分别分配列表,并按可编程序控制器内部软继电器的编号范围,给每个信号分配一个确定的编号;

③根据控制要求设计梯形图;

④编写程序清单。梯形图上的每个逻辑元件均可相应地写出一条命令语句,编写程序应按梯形图逻辑行和逻辑元件的编排顺序由上至下,由左至右依次进行。

完形填空

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项,选项中有两项为多余选项。

Is bottled water better for you than tap? Or should you choose vitamin-enriched water? Experts say, skip it all. None of these products is likely to make you any healthier. Below, we look at four major myths about the benefits of drinking water. 小题1:Experts say there’s an easy way to judge. If you are not thirsty, your fluid intake is likely “just right”

Myth No 1: Drink eight glasses each day.

Scientists say there’s no clear health benefit of drinking so much water a day. 小题2:“Nobody really knows,” says Dr. Stanley Goldfarb, a kidney expert at the University.of Pennsylvania.

Myth No.2:Lots of water equals healthier skin.

The body is already 60 percent water. 小题3:Adding a few extra glasses of water each day has a limited effect. “It’s such a tiny part of what’s in the body,” says Goldfarb. “ It’s very unlikely that one’s getting any benefit.”

Myth No.3: 小题4:

A more accurate statement may be: Drinking water is a helpful tool for dieters. “Water is a great strategy for dieters because it has no calories,” says Madeline Fernstrom of the University of Pittsburgh. “So you can keep your mouth busy without food and get a sense of satisfaction.” But water is not magical, she adds. “Other zero-calorie options such as diet sodas are fine, too.”

Myth No. 4: It’s easy to get dehydrated(脱水的) during a workout.

Dehydration sets in when a person has lost 2 percent of his or her body weight.小题5:“It’s also obvious that individuals in hot, dry climates have an increased need for water,” says Goldfarb. “But for a walk in the park, no water bottle is necessary.”

A.So where does the standard advice come from?

B.But it’s unclear whether these changes are clinically significant.

C.So for a 200-pound man, this means losing 4 pounds of water.

D.Drinking extra water leads to weight loss.E.Drink as much water as you can.

F.So, if you take a 200-pound man, he’s 120 pounds of water.

G.But first, how do you know if you’re drinking enough water?

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