Which describes an achievement of Emperor Yangdi that helped unite China? He built the Great Wall of China to keep out invading Mongol hordes.

He designed a plan for a series of interconnecting canals.

He made Marco Polo an honored guest at the imperial court in Beijing.

He introduced terraced farming to produce more food.

He designed a plan for a series of interconnecting canals.

Explanation:

Emperor Yangdi helped to unite people in China by building a vast network of interconnecting canals. The constructing of the Grand Canal connected the northern and southern regions in China. Through the canal, people were able to connect from the far region and transport goods to the capital and other places. It was also used for supplying food to the northern border armies with food from the south.

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- "schenck v. united states, case in which the u.s. supreme court ruled on march 3, 1919, that the freedom of speech protection afforded in the u.s. constitution's first amendment could be restricted if the words spoken or printed represented to society a “clear and present danger.” "

- speech aimed to potentially create danger could be banned.

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