问题
单项选择题
主令控制器控制的电力拖动系统中，零位保护是如何实现的？（）
A.通过在所有档位设自保环节实现
B.设零压继电器，并在主令控制器零位档设零压继电器自保环节实现
C.设零压继电器，并在主令控制器加速档位设自保环节实现
D.设零压继电器，并在主令控制器方向控制档位设自保环节实现
答案
参考答案：B
搜题请搜索小程序“爱下问搜题”
主令控制器控制的电力拖动系统中，零位保护是如何实现的？（）
A.通过在所有档位设自保环节实现
B.设零压继电器，并在主令控制器零位档设零压继电器自保环节实现
C.设零压继电器，并在主令控制器加速档位设自保环节实现
D.设零压继电器，并在主令控制器方向控制档位设自保环节实现
参考答案：B
| 阅读理解。 | ||
| Do you go to the movies during the holidays? What do you eat there? Popcorn (爆米花)? Yes, of course! More and more Chinese youth now like to eat popcorn when they watch movies at the theater. However, it may be the Americans who love popcorn the most. Americans do fun things with their popcorn. They like to put butter on their popcorn. But that's not all; they also like other kinds of things like chocolate, marshmallows (果汁软糖) and even cheese! Americans like to eat popcorn as a snack (小吃). These days, there are a lot of "low-fat" kinds of popcorn in US shops to keep people healthy.
| ||
| 1. Many Chinese youth like to eat _____ at the theater. | ||
| A. Nothing. B. Popcorn. C. Chocolate. | ||
| 2. According to the passage, _____ love popcorn the most. | ||
| A. Chinese B. Frenchmen C. Americans | ||
| 3. The low-fat popcorn is popular in US shops because _____. | ||
| A. it is not a snack B. it is healthy C. it is cheap | ||
| 4. Americans couldn't eat popcorn at the theater because it's _____. | ||
| A. noisy B. unhealthy C. expensive | ||
| 5. The main idea of the passage is that _____. | ||
| A. popcorn is now popular at theaters B. Americans eat popcorn the most C. People eat popcorn as a snack |
