1) The force of……………keeps the planets on their paths around the sun a) air resistance b) gravity c) . friction d) electricity 2) ………….is (are) the center of the solar system a) The Earth b) The moon and Earth c) The sun d) The sun and Earth 3) Gravity is………….force that holds all objects in their places. a) visible pulling b) invisible pulling c) visible pushing d) invisible pushing

排行榜

视觉风格

选项

切换模板

恢复自动保存: