【单选题】【消耗次数:1】
I haven’t finished my composition . I________ for two hours and a half.
have written it
have been writing it
wrote it
am writing it
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相关题目
【单选题】 I haven’t finished my composition . I ________ for two hours and a half.
①  have written it
②  have been writing it
③  wrote it
④  am writing it
【单选题】 I haven’t finished my composition. I ___ for two hours and a half.
①  ?have written it
②  ?have been writing it
③  ?wrote it
④  am writing it
【单选题】 I often ______ the cooking for my family, but recently I have been too busy to do it.
①  will do
②  do
③  am doing
④  had done
【单选题】 I have been looking forward to ____ from my parents.
①  :hear
②  :being heard
③  :be heard
④  :hearing
【单选题】 ( ) he finished writing the composition in such a short time surprised us all.
①  What
②  How
③  That
④  If
【单选题】 I am ____ grateful for the many kindnesses you have shown my son.
①  excessively
②  much
③  certainly
④  exceedingly
【判断题】 I have finished the book.
①  正确
②  错误
【单选题】 I have_______ finished the homework.
①  yet
②  already
③  still
【单选题】 The reason _________ I am writing this letter is to tell you about the meeting on Saturday.
①  because
②  why
③  for
④  as
【单选题】 I haven’t read ____ of his books, but judging from the one I have read I think he’s a very promising writer.
①  any
②  none
③  both
④  either
随机题目
【单选题】 电子计数器是一种最常见、最基本的数字化仪器,它利用数字电子技术对在给定时间内通过的脉冲进行计数并显示其计数结果。
①  正确
②  错误
【单选题】 计数及显示电路用于对主门输出的脉冲计数并以十进制显示计数结果。
①  正确
②  错误
【单选题】 用计数器测频的误差主要包括:(? )
①  量化误差、触发误差
②  量化误差、标准频率误差
③  触发误差、标准频率误差
④  量化误差、转换误差
【单选题】 下列哪种方法不能减小量化误差:( ?)
①  测频时使用较高的时基频率
②  测周时使用较高的时基频率
③  采用多周期测量的方法
④  采用平均法
【单选题】 用计数器直接测周的误差主要有三项:即量化误差、触发误差以及标准频率误差。
①  正确
②  错误
【单选题】 根据所测参数的类型,半导体分立器件测量仪器大致可分为()。①直流参数测量仪器②交流参数测量仪器③极限参数测量仪器④晶体管特性图示仪
①  ①②③
②  ①②④
③  ①②③④
④  ②③④
【单选题】 数字集成电路主要有_______和_______集成电路等。
①  MNE和CMOS
②  TTL和CMOS
③  TTL和MDIB
④  MNE和MDIB
【单选题】 直流测试包括输出高电平、输出低电平、______、______、电源功耗电流等。
①  输出高电平电流、输出低电平电流
②  输入高电平电流、输出低电平电流
③  输出低电平电流、输入低电平电流
④  输出高电平电流、输入高电平电流
【单选题】 交流测试包括延迟_____、最高时钟频率。
①  时期
②  高度
③  时间
④  时刻
【单选题】 阻抗测量一般是指电阻、电容、电感及相关的Q值、损耗角、电导等参数的测量。
①  正确
②  错误