Same for gravity, two concepts, so it's -- which is quite humbling, as a, you know, if you're a teacher, and you look before and after, that's quite worrying. They do worse in tests afterwards, after the teaching.
重力知识也一样，两个不同概念，这实在可悲 如果你是个老师，看见受教前和受教后的差别 实在令人忧心，学童在受教后考得更差