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【单选题】
正弦脉宽调制(SPWM)的技术和实现原理,下列叙述哪个是不正确的?( )
A.
SPWM就是实现用一系列等幅不等宽的脉冲来代替正弦波
B.
要想改变等效输出正弦波,只要按统一比例改变各脉冲的宽度
C.
SPWM等幅不等宽的脉冲中,宽度的变化符合正弦规律。
D.
SPWM技术采用等幅的矩形波作为载波信号
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【单选题】“全世界无产者联合起来”是()的口号。
A.
正义者同盟
B.
共产主义者同盟
C.
社会主义者同盟
D.
共产主义者同盟
【单选题】“全世界无产者联合起来”是()的口号。
A.
正义者同盟
B.
共产主义者同盟
C.
社会主义者同盟
D.
工人同盟
【判断题】局部均衡是马歇尔提出的,均衡分析是各种经济变量同时达到稳定状态。
A.
正确
B.
错误
【单选题】Questions 12 to 15 are based on the conversation you have just heard.
A.
They could break people's legs
B.
They could sometimes terrify adults
C.
They could fly against a strong wind
D.
They could knock people unconscious
【单选题】鬼子在打洛江里扔下了( ) 具尸体。
A.
七十多
B.
六十多
C.
九十多
D.
八十多
【单选题】Questions 12 to 15 are based on the conversation you have just heard.
A.
His favorable recommendations.
B.
His outstanding musical talent.
C.
His academic excellence.
D.
His unique experience.
【单选题】Questions 12 to 15 are based on the conversation you have just heard.
A.
No melting has been observed in Antarctica.
B.
The past several winters have been unusually severe.
C.
Noting unusual has happened in other parts of Antarctica.
D.
The ice shelves had remained intact for centuries despite the weather changes.
【单选题】Questions 12 to 15 are based on the conversation you have just heard.
A.
She was late for the interview.
B.
She missed yesterday's class.
C.
She lost her part-time job in IKE
D.
she gave up the chance to work in IKE
【判断题】“全世界无产者,联合起来!”是共产主义者同盟的口号。()
A.
正确
B.
错误
【单选题】天气是指某一特定区域,()。
A.
气象要素的一年平均特征(其中包括极值)
B.
在较长时间内各种气象要素的综合表现
C.
气象要素的多年平均特征(其中包括极值)
D.
在较短时间内各种气象要素的综合表现
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