话音信号的频率范围约为50至10000HZ,而其主要能量集中在()
A.100至2000Hz
B.300至3400Hz
C.1000至5000Hz
参考答案:B
— Time________.It's likely that we'll miss the deadline.
— Don't worry.We have already got through 80% of the job. [ ]
A. is running out
B. has run out
C. is being running out
D. has been run out
Everyone knows that China’s Bristles are of superior quality()those from other countries.
A.with
B.to
C.for
D.than