Vietnam War lasts for 20 years, from the year 1955 to 1975. Vietnam had been under French colonial rule since the 17th century.
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In 1975, communist forces ended the war by seizing control of South Vietnam, and the country was unified as the Decomatic Republic of Vietnam the following year.
A. 对
B. 错
In 1845, Mexican-American war erupted. America defeated Mexico and occupied a large area of its land(today’s Texas).
A. 对
B. 错
In September 2015, Chinese president Xi Jinping put forward the concept of building the new Silk Road economic belt and the 21st Century Maritime Silk Road for the first time.
A. 对
B. 错
当不同变换区间长度与N成倍数关系时,即N'=rN,N'点的DFT结果为G(k),N点的DFT结果为X(k),则G(k)的谱线要比X(k)的()且( )
A. 疏;完全重合
B. 疏;部分重合
C. 密;完全重合
D. 密;部分重合