According to paragraph 3, how was the class system structured？
An upper class and a lower class
B. Slaves, free people, and a ruling class
C. A king, an army, and slaves
D. Intellectuals and uneducated farmers and workers
Why is wireless recharging a depressing promise for experienced observers of the electronics industry？
A. It is not easy to put the theory into profitable production,
B. Wireless recharging needs new theories besides Faraday's.
C. Wireless recharging can't make profit for businesses.
D. It is hard to challenge the monopoly of Splashpower.
Which of the following statements most accurately reflects the author's opinion about life
A. Life is probably limited to planets in the inner solar system.
B. There is a large body of evidence supporting life on Mars.
C. There is little probability of life on other planets.
D. We should explore our solar system for conditions that support life.
The word crucial in the passage is closest in meaning to
A. fundamental
B. arbitrary
C. disruptive
D. suitable
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