The scientific methods involved in this paper are:
Guess: Guess that "it's raining again" is two dawns, that is, the total solar eclipse occurs in the morning.
Observation: When the total solar eclipse occurred, northern Xinjiang just broke dawn. The observation of this total solar eclipse …
Calculation: After calculation, China scientists …
Verification: It provides an important basis for the research of "Xia, Shang and Zhou Dating Project" in China.
(2) Total solar eclipse is a kind of solar eclipse, that is, the astronomical phenomenon that the sun is completely covered by the moon. If the sun, the moon and the earth are in a straight line, the moon blocks the sunlight that hits the earth, and the shadow behind the moon just falls on the earth. At this time, only people in the shadow of the moon can see the total solar eclipse, so B is the earth.
So, the answer is: the straight-line propagation of light; Guess; Observe; second