He was about to go to bed______ the doorbell rang:
A. while
B. as
C. before
D. when
查看答案
______I listen to your advice, I get into trouble.
A. Every time
B. When
C. While
D. Until
She had a stomachache ______she ate something bad.
A. so
B. because
C. or
D. although
以下为二进制码,其中功率谱中离散谱分量的码是( )。
A. 等概单极性码
B. 不等概单极码
C. 等概双极性码
D. 不等概双极性码
设某传输码序列为+1-100-1+100+1-1000-1+100-1,在接收端正确恢复出的数字序列为____。