问题
单项选择题
集成运算放大器工作于线性区时，其电路的主要特点是（）。
A.具有负反馈
B.具有正反馈
C.具有正反馈或负反馈
D.无须正反馈和负反馈
答案
参考答案：A
搜题请搜索小程序“爱下问搜题”
集成运算放大器工作于线性区时，其电路的主要特点是（）。
A.具有负反馈
B.具有正反馈
C.具有正反馈或负反馈
D.无须正反馈和负反馈
参考答案：A
An eight-year-old child heard her parents talking about her little ___1______ All she knew was that he was very sick and they had no money left. When she heard her daddy say to her 2 mother with whispered desperation（绝望）, "Only a miracle（奇迹） can save him now", the little girl went to her bedroom and took out her piggy bank. She poured all the change out on the floor and counted it carefully. Then she 3 her way six blocks to the local drugstore（药店）. "And what do you want?" asked the chemist. "It’s for my little brother," the girl answered back. "He’s really, really sick and I want to buy a 4 . His name is Andrew and he has something bad growing inside his head and my 5______says only a miracle can save him." "We don’t sell miracles here, child. I’m sorry," the chemist said, smiling 6 at the little girl. In the shop was a 7 customer. He stooped down and asked the little girl, "What kind of miracle does your brother need?" "I don’t know," she replied. "He’s really sick and mommy says he needs 8 . But my daddy can’t pay for it, so I have brought my 9 ." "How much do you have?" asked the man. "One dollar and eleven cents, _____10 ____I can try and get some more," she answered quietly. "Well, what a coincidence（巧合）," smiled the man. "A dollar and eleven cents? The 11 price of a miracle for little brothers. Take me to where you live. I want to see your brother and meet your parents." That well-dressed man was Dr Carlton Armstrong, a surgeon（外科医生）. The operation was completed without 12 and it wasn’t long before __13__________was home again and doing well. The little girl was____14______. She knew exactly how much the miracle cost ... one dollar and eleven cents ... plus the 15 of a little child. 小题1:A dog B sister C brother. D father
小题14:A satisfy B happy C frightened D angry
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