少一半的英文：
half as many
half as long again as
half as much

参考例句：

The new engine may use half as much oil as the old one.
新引擎的油耗比旧引擎少一半。

half是什么意思：
n. 一半；半场，半局
adj. 一半的，不完全的
adv. 一半地，部分地

That is a job and a half.
那是非常困难的工作。

half-believe ";"half believing, half doubting
将信将疑

many是什么意思：
det. 许多，大量；大多数人
pron. 许多；许多人
adj. 许多的

The possibilities are many.
有许多可能。

It has many advertisements and many different sections.
星期日报有很多广告和许多栏目。

There are many, many ramifications and many things we could talk about.
有许多许多的分枝以及我们可以谈论的许多事情。

long是什么意思：
adj. 长的；长时间的；冗长的；长音的
adv. 长久地，长期地；始终
n. 长时间，长时期；长音节
v. 渴望
abbr. 经度，经线

But perhaps not for long.
但这并不会持续太长时间。

It will take a long time to read through this long story.
要读完这长篇故事要花相当长的时间。

propagation of long and very long wave in the ionosphere
电离层长波和超长波传播