_______receives only a small portion of the total amount of the sun's energy.

_______receives only a small portion of the total amount of the sun's energy.
a The earth's surface b The surface of earth
请问选哪一个啊?
2、Numerous materials are available to ______
a today's designers b today's of designers
3、_____is too much for a little boy to carry.
a A bike's weight B The weight of a bike