I can certainly try to write the number 13 there, but bam, my program very likely will crash if this chunk of memory was not given to me previously by the operating system and maybe it is owned by the operating system.

我当然可以在那里写下数字13，但是“嘣“,如果这块内存不是系统预先给我的,我的程序很可能会崩溃,可能这块内存,是系统本身使用的。

哈佛公开课 - 计算机科学课程节选

Only the operating system has controlling of byte zero NULL in the computer's RAM and so if a function ever returns null, aka zero, well, something must have gone wrong because that can't possibly belong to me that memory because by human convention zero is owned by the operating system; not by a program I wrote.

只用操作系统在内存中能够控制,字节0，并且如果一个函数返回，或者说0，好的，可能出错了,因为那可能是不属于我的内存,因为惯例上，0是由操作系统拥有的,而不是由我的程序拥有的。

哈佛公开课 - 计算机科学课程节选

So, these memory cells are a way that your immune system keeps track of antigens that it's been exposed to for even if maybe the plasma cells that were producing antibody in response to the initial exposure have died and disappeared.

所以,这些记忆细胞,是人体免疫系统记忆抗原的一种方法,即使由浆细胞产生的抗体,在初次免疫应答中全部被消灭,记忆细胞仍然能迅速分化为抗体分泌细胞

耶鲁公开课 - 生物医学工程探索课程节选