问题 实验题

图示为一简单欧姆表原理示意图,其中电流表的满偏电流Ig=300 μA,内阻Rg=100 Ω,可变电阻R的最大阻值为10 kΩ,电池的电动势E=1.5 V,内阻r=0.5 Ω,图中与接线柱A相连的表笔颜色应是________色。按正确使用方法测量电阻Rx的阻值时,指针指在刻度盘的正中央,则Rx=________kΩ。若该欧姆表使用一段时间后,电池电动势变小、内阻变大,但此表仍能调零,按正确使用方法再测上述Rx,其测量结果与原结果相比将________(填“变大”“变小”或 “不变”)。

答案

红,5,变大

阅读理解
Our lifestyles today are very busy. We have family, school, sports, entertainment and social activities to fit into a time that seems never enough. We need to be healthy to meet the demands of daily life. But what does it mean to have a healthy lifestyle?
To have a healthy lifestyle, we need to:
◆ eat different kinds of healthy food most of the time
◆ do exercise often
◆ have time to relax
◆ get enough sleep to give our bodies time to grow healthy and strong
Read about a normal day in the lives of two children.

Abbey gets up at 7:00 am, feeds the dog, and has cereal and a glass of juice for breakfast.  She walks to school with her friend, Julia. She has a bag of chips for a morning snack, drinks water, and has a chicken and lettuce sandwich with a banana for lunch. She likes to play soccer with her friends at lunch and morning break time. She walks home with Julia, has some crackers with cheese and juice for afternoon snack and plays with the dog for a while. She plays computer games for an hour or two before dinner, then has a shower and does her homework. She watches her favorite television show for an hour, then usually goes to bed at about 9:30 pm.
Carl gets up at 8:30 am and has two pieces of bread with jam and a glass of milk for breakfast. His mother drives him to school on her way to work. He eats cookies with juice for morning snack and a pot pie ordered from the school lunch room with juice for lunch. He likes to play card games with his friends at lunchtime and climb the fixed equipment at morning break time. He catches the bus home, has a cereal bar and a can of soda for afternoon snack, then watches some television. He has a shower before dinner, then plays the computer for an hour or two. He goes to bed at about 10:30 pm.
No matter which kind of lifestyle you agree on, just remember it’s important to balance all aspects of life.
小题1:About a healthy lifestyle, the writer doesn’t talk about __________.
A.dietB.exerciseC.relaxationD.medicine
小题2:What can we learn from the article?
A.Abbey plays soccer with her friends at school.
B.Abbey does her homework first after school.
C.Carl goes to school by bus every day.
D.Carl has juice for breakfast.
小题3:Where is the article probably from?
A.A health magazine.
B.A clothing website.
C.A sports guidebook.
D.A travel advertisement.
多项选择题