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【简答题】
模拟信号传输的基础是载波,载波具有三个要素,即幅度、频率和_______。数字数据可以针对载波的不同要素或它们的组合进行调制,有三种基本的数字调制形式,即移幅键控法ASK、移频键控法FSK和移相键控法PSK。
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举一反三
【单选题】The conclusion which can be drawn safely from the second paragraph is that ______.
A.
a population growth from natural increase leads to a greater proportion of the workforce
B.
a large population does not necessarily mean a higher proportion of workforce
C.
the larger the number of the aged in a population, the higher the proportion of the workforce
D.
if the population has an evenly spread age distribution, the workforce will be lower
【单选题】.Most of the citizens didn’t know what had________just now.
A.
come through
B.
come into
C.
come along
D.
come about
【单选题】听力原文：W: Come swimming with me? M: Sorry, but I'm up to my neck in work. Q: What's the man's problem? (13)
A.
He injured his neck.
B.
He's tired of swimming.
C.
He's too busy to go swimming.
D.
He's afraid to swim in deep water.
【简答题】长度测量工具包括: 和 。
【单选题】下列有关交通规划初步方案的预测内容中有误的一项为( )。
A.
包括车辆、交通量增长的预测
B.
包括交通的产生、分布和在道路上交通量的分配的预测
C.
包括交通工具生产数量、车辆速度的增长预测
D.
包括根据交通量对道路面积和密度的预测
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