题目选项分析

Theorists of expeditions to extrasolar planets have typically been concerned with exceeding the speed of light and to what degree it could be, but aerospace engineers have long expected that the greatest obstacles to the manned exploration of other solar systems would be the difficulty of prolonged food storage and exposure to cosmic radiation.

Theorists of expeditions to extrasolar planets have typically been concerned with exceeding the speed of light and to what degree it could be, but aerospace engineers have long expected that the greatest obstacles to the manned exploration of other solar systems would be the difficulty of prolonged food storage and exposure to cosmic radiation.