THE waves of invasion and immigration that have, from time to time, swept over the British Isleshave led some to refer to Britons as a mongrel nation.

外部入侵与移民浪潮时常席卷不列颠群岛，因此，有人将英国称为混血国。

But low-octane engines don’t compress enough for high-octane fuels, and there isn’t enough time between the spark and the gas being swept out of the chamber for all that fuel to be used up.

但是低辛烷值发动机不能压缩足够的高辛烷值燃料，而且在火花和气体被扫出燃烧室之间没有足够的时间让所有燃料都用完。