问题
选择题
如图所示，水平传送带以速度
匀速前进.上方料斗中以每秒50kg的速度把煤粉竖直落到传送带上，然后一起随带运动，如果要使传送带保持原来的速度匀速前进，则皮带机应增加的功率为（
）
A．100W
B．200W
C．500W
D．无法确定
答案
答案：B
搜题请搜索小程序“爱下问搜题”
如图所示，水平传送带以速度匀速前进.上方料斗中以每秒50kg的速度把煤粉竖直落到传送带上，然后一起随带运动，如果要使传送带保持原来的速度匀速前进，则皮带机应增加的功率为（）
A．100W
B．200W
C．500W
D．无法确定
答案：B
完形填空 In the United States, headmasters and teachers discipline (惩戒) students in several ___1__. The teacher often writes or calls the student’s ___2___. Sometimes students have to stay at school for an extra hour. If a student behaves very ___3___，the headmaster can suspend (暂停学生上课) the student. The student cannot ___4___ for one, two, or three days. Mr. Lazares didn’t like to suspend students. When he suspended some students, they were ___5___. “A three-day holiday!” they thought. One day, a boy named Robert was in Mr. Lazares’s office. The boy was not behaving well in class. Mr. Lazares telephoned the boy’s parents. “If you come to school with your son, I won’t ___6___ him,” he said. The boy’s father came to school and went with his son to every class.Other students___7___ the boy and his father. The boy was embarrassed. After that, he behaved ___8___. He didn’t want his father to come to school again. Other students behaved better, ___9___. They thought, “I don’t want my parents to come to school!” That year about 60 parents came to school with children who didn’t behave well. The next year only ___10___ parents had to come to school. The students were behaving better. 小题1:A. A. streets B. roads C. ideas D. ways
|