What does it refer to in I saw it, I saw it! ？ （lines 3–4） （Text 1A）（）
A. the cenote
B. the zenith light
C. the stone sundial
D. the mouth of the well
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Why is farming particularly difficult for the Maya？ （Text 1A）（）
A. Rivers flood regularly
B. Rain does not sink into the ground
Crops like corn suck nutrients from the soil
D. There are not enough farmers during harvest time
How did the climate in Angkor change in the 1300s？ （Text 1B）（）
A. Winters became too cool to grow rice
B. Rising temperatures caused great discomfort
C. There were terrible storms and constant flooding
D. Weather conditions became more extreme
Both Sally and Sam receive a 10% raise in a single year. Sally increases her demand for ground beef whereas Sam decreases his demand for ground beef（）
A. This is impossible
B. This is only possible if Sally considers ground beef an inferior good, and Sam views it as a normal good
C. This is only possible if Sally has lower income than Sam
D. This is only possible if Sally considers ground beef a normal good and Sam views it as an inferior good
The slope of the total product curve always equals（）
A. the ratio of the marginal product and the average product
B. the change in input divided by the change in output
C. the average product of the input
D. the marginal product of the input
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