单项选择题

What does the passage mainly discuss

A．The production of solar light and heat.
B．The physical and chemical nature of life.
C．The conversion of hydrogen to helium.
D．Radiation in the X-ray part of the spectrum.

<上一题目录下一题>

热门试题

单项选择题

The passage indicates that, in comparison to radio waves, gamma waves ______.

A．are not as long
B．produce louder sound
C．are less magnetic
D．do not form in the Sun's center

单项选择题

According to the passage, energy is released in the Sun when ______.

A．helium atoms bind with each other
B．gamma radiation escapes from the spectrum
C．radiation is absorbed by helium
D．nuclei of hydrogen atoms collide