在齿轮传动中，外啮合齿轮旋向相同，内啮合旋向相反。
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News item 3Listen to the news report and choose the best answer to each question you hear.
A. He is frustrated.
B. He is happy.
C. He is upset.
D. He is angry.
News item 3
A. Farms in New York and Canada
B. A restaurant in California
C. The USDA offices
D. Factories in France
News item 4Listen to the news report and choose the best answer to each question you hear.
A. Because these eggs come from chickens that eat worms.
Because these eggs come from chckens that eat California lettuce and Washington apples.
C. Because these eggs come from chickens that drink milk, and they’re never fed antibiotics.
D. Because these eggs come from chckens thateat grain he grows himself, and they’re never fed antibiotics.
News item 4
A. Eggs, broiler chicken, and lettuce.
B. Eggs, broiler chickens, and apples.
C. Milk, eggs, and broiler chickens.
D. Milk, eggs and apples.
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