1. What does the professor main discuss?
A. ways that stars become nebulae
B. reasons that nebulae appear to give off blue light
C. difference between nebulae and stars
D. a basis for classifying types of nebulae
2. What point does the professor make about Orion’s sword?
A. It points toward a nebula in the constellation taurus.
B. It contains a nebula that looks like a star to the naked eye.
C. It contain stars whose light is a reflection of other nearby stars.
D. It contains two stars that are remnants of a supernova.
3. What does the professor say about the origin of the crab nebula?
A. It was formed when interstellar gas clouds combined.
B. It was created by an exploding star.
C. It did not emit when it was first formed.
D. It was formed in the same way as many reflection nebulae.
4. Based on the lecture, which answer choices describe emission nebulae and which describe reflection nebulae?
Click on an answer choice, Then drag in to the space where it belongs. One of The answer choices will not be used
emission nebulae reflection nebulae
Answer Choices
A. They give off red light.
B. They give off blue light.
C. They can only be seen from locations near the equator.
D. They do not contain glowing gas.
5. What is a typical characteristic of dark nebulae?
A. They are obscured from view by nearby stars.
B. They are located in parts of the sky that do not contain bright stars.
C. The dust and gas they contain are too dense to let light through.
D. They are too hot to emit radiation in the visible range.
6. Why does the professor say this:
A. To clarify his previous statement
B. To call attention to an unusual phenomenon
C. To emphasize a feature of all types of nebulae
D. To repeat a point he made earlier
答案：D B B A/BD C D