Because on second exposure there's another population of cells that I haven't mentioned before that remain after the primary exposure and those are called memory cells, they're down here.

因为在再次免疫中,有另外一些细胞,我之前并没有提到过它们,在初次免疫结束后保留下来的细胞,被称为记忆细胞,它们在下面

耶鲁公开课 - 生物医学工程探索课程节选

The Law of Inertia says that, "If a body has no forces acting on it, then it will remain at rest if it was at rest to begin with, or if it had a velocity to begin with, it will maintain that velocity."

惯性定律就是,"如果一个物体不受外力作用,那么静止的物体依然保持静止,如果物体有个初速度,那么就保持此速度不变"

耶鲁公开课 - 基础物理课程节选