Is the space travel to other planets safe?
举一反三
- While space travel
- 学起: Space travel is dangerous and the astronauts in space have to ______ many discomforts (不适) in their rockets.
- The passage is mainly about ______. A: the development of space' technology B: the obstacles and prospects of space transportation C: the public interests in space travel D: the growth of space business
- Are there any ______for believing that there is life on other planets A: facts B: bases C: grounds D: foundations
- According to Newton's principle ______. A: the force of gravity keeps planets orbiting around the sun rather than flying off B: the sun is the most massive object, making up 99.8 percent of the mass of the solar system C: the amount of mass determine how fast the objects travel as they orbit each other D: Pluto receives the least force of gravity from the sun of all the planets in the solar system