Day133 练习内容（TPO38-L4）
4.According to the professor, what could have occurred when a proto-planet in the outer accretion disk reached a mass of five to ten Earths?
A. It started to shed grains of rock and metal into the solar system.
B. Its gravity began to pull in huge amounts of the surrounding gas.
C. Its gravity caused clumps to form in the surrounding gas.
D. It collided with smaller proto-planets.
5.According to the professor, what are two claims of the disk-instability theory? Click on 2 answers
A. Gas planet formation did not begin with a solid core.
B. Gas planets cannot form in extremely cold temperatures.
C. Gas planet formation can occur anywhere in the accretion disk.
D. Gas planets form over a relatively short time.
6.Which is right about the professor’s opinion about the disk-instability theory?
A. It differs from the core-accretion theory in relatively insignificant ways.
B. It does not take into account the amount of time needed for gas planets to form.
C. It is more applicable to star formation than the core-accretion theory is.
D. Solid particles are believed to own a small proportion of the outer accretion disk.
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