Think about it. If you were an engineer and I told you that you had to build an automobile, but it had to start off to be this big, then it had to grow to be full size and had to work every step along the way.
试想你是一个工程师，我告诉你 你得造一辆汽车，一开始只能有这么点儿大 然后要渐渐长成，而且在每个阶段都能工作