motion in a straight line的用法和樣例：
例句
- The tendency of a body in motion to continue in motion along a straight line is known as inertia.
運動(dòng)物體繼續作直線(xiàn)運動(dòng)的傾向叫慣性。 - A little known theory of Kepler's held that comets were celestial bodies moving along straight lines.
另一個(gè)鮮為人們所知的開(kāi)普勒理論認為，彗星是沿直線(xiàn)運動(dòng)的天體。
