2026年2月托福机经套卷(第1套)Read an Academic Passage / 25 道题

Twin Stars

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Twin Stars Stars form in the relatively dense, egg-shaped cores of molecular clouds made of dust and gases. Scientists mapping these dense cores must use radio waves to penetrate the dust and gases that prevent light from escaping molecular clouds; satellite images of these regions show nothing but large, black areas of space. Recent observations of the Perseus molecular cloud may have surprising implications for previously accepted conclusions about the Sun. A radio wave sweep of the Perseus cloud's dense cores revealed that the youngest stars existing in the cloud all occurred in pairs, or binary twins, orbiting a common point. Stars of older binary systems, of which there were fewer, appeared closer together than stars of younger binary systems. Scientists used current knowledge about stellar growth, decay, and destruction to predict the paths along which binary stars traveled throughout the molecular cloud. Their estimates would align with current understandings only if all stars approximately the same size as the Sun had begun as members of a binary system that first moved closer to each other and later separated. This rule would also apply to the Sun, whose twin likely separated following approximately one million years of coexistence.

Question 1查看单题

Which of the following best summarizes the main point of the passage?

ABinary stars alternate between separating and getting closer over time.

BStar development takes place in the dense cores of molecular clouds.

CThe Sun formed in the same way that the Perseus molecular cloud did.

DStars the size of the Sun begin their development with a binary twin.

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正确答案：D

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Question 2查看单题

The word "penetrate" in the passage is closest in meaning to

Apush aside