Question

read the passage. then answer the question that follows.

space travel is one of humanity’s greatest challenges and accomplishments. beginning with ancient chinese rockets, it took thousands of years to invent something powerful enough to enter outer space. scientists needed to solve two fundamental problems: create something light enough to leave the atmosphere but large enough to safely carry humans, and create something that could survive re - entering earth’s atmosphere. the friction between a speeding object and the atmosphere is so great that the object could burn up in seconds. this is why many small meteors never make it to the surface. while this is great for protecting earth from harm, it poses a major obstacle for sending spacecraft to and from space. a spaceship needs to travel at about 25,000 miles per hour to leave earth. to avoid burning up, some spacecraft have heat shields made of ceramic tiles or other heat - resistant materials.

which two sentences could be added to support the information in the passage?

a after repeated uses, the first space shuttle began to lose their heat - resistant tiles, and this threatened the missions.

b the first rockets built in china were not large enough to carry enough gunpowder to blast through the pull of earth’s gravity.

c the united states invented and tested several rockets to assess the viability of humans orbiting earth and coming back safely.

d several different companies, including car manufacturers and airplane makers, took part in different stages of rocket development.

e meteors that are large enough will burn off much of their mass as they enter the atmosphere but will still survive and hit earth’s surface.

f the saturn rocket provided the necessary thrust to lift a human - occupied space capsule, which would re - enter the atmosphere safely.

Explanation:

To support the passage about space travel challenges (like heat resistance, rocket development for human spaceflight), we analyze each option:

• Option A: Talks about space shuttle heat tiles issues, relevant to heat resistance challenge.
• Option C: US testing rockets for human orbital viability, supports human spaceflight development.
• Option F: Saturn rocket's role in safe re - entry, supports spacecraft design for re - entry.

(Note: Option B is about ancient Chinese rockets' gunpowder, less relevant. Option D is about company involvement, not core challenge. Option E is about meteors, not space travel tech.)

Answer:

A. After repeated uses, the first space shuttle began to lose their heat - resistant tiles, and this threatened the missions.
C. The United States invented and tested several rockets to assess the viability of humans orbiting Earth and coming back safely.
F. The Saturn rocket provided the necessary thrust to lift a human - occupied space capsule, which would re - enter the atmosphere safely.