内存开销非常小：基本上每个接口需要额外4个字节（对象实例数据里虚函数表指针），加上引用计数的4个字节。

Overhead in memory is very small: You basically have a 4- byte overhead per interface (the vtable pointers in the object's instance data) plus 4 bytes for the reference counter.

youdao

上述各种问题在美国也很常见：美国各高校里分数虚高问题频频发生；哪儿可以上网，哪儿就会有抄袭剽窃现象，而且愈演愈烈。

Some of this is standard fare: American universities suffer periodic spasms over grade inflation; plagiarism is on the rise wherever students can use the internet.

youdao

我觉得这张相片里我的脸有点虚。

I think my face in this picture is a bit out of focus.

youdao