题目内容

My father___________ ill yesterday．

A. isn't
B. aren't
C. wasn't
D. weren't

查看答案

搜索结果不匹配？点我反馈

更多问题

The twins __ in Beijing last year. They here now.

A. are; were
B. were; are
C. was; are
D. were; was

Shelivedtherebefore she____toChina.

A. came
B. comes
C. come
D. coming

I_but_nothing.

A. was listened; was hearing
B. listened; heard
C. have heard; listened
D. heard; listened

数字基带传输系统中,接收滤波器的作用是( )。

A. 产生适合信道传输的信号
B. 在噪声背景下用来判定与再生基带信号
C. 接收信号和尽可能滤出信道噪声和其他干扰
D. 使发射端和接收端在时间上同步