rectilinear motion assumption

例句：

1. 1.The scientist made a significant discovery about the nature of matter during his research.
   科学家在其研究中发现了关于物质本质的重要发现。
2. 2.The new model assumes that the earth moves around the sun.
   新模型假定地球绕太阳运行。
3. 3. The assumption is that the temperature will remain constant throughout the day.
   假设是，温度在整个白天将保持恒定。