四级的英文：
four-stage

参考例句：

In a spherical nucleus, the coupling term implies an interweaving of the quadrupole and dipole motion
对球形核中的耦合项意味着四级运动和偶极运动间的交织。

There 's a moderate east breeze tomorrow.
明天有四级东风

There will be a moderate north breeze tomorrow.
明天将有四级北风

There will be a moderate breeze tomorrow.
明天有四级风

Pass the College English Test band 4; obtain a certificate of CET-6
通过大学英语四级考试/获六级证书

English level at CET 4 and proficient with MS Office operation
英语达四级水平,熟练电脑OFFICE操作

it was like trying to douse a 4-alarm Fire with a water pistol
这就像企图用一把水枪去扑灭一场四级火情警报的大火一样。

A great many proteins, especially enzymes, are oligomeric and consequently possess quaternary structure.
很多蛋白质尤其是酶类,是低聚物,因此拥有四级结构。

four是什么意思：
n. 四；四个；第四

Four divides eight.
4能除尽8。

We have four terms a year.
我们每年有四个学期。

The hunters bagged four deer.
猎人们捕杀了4只鹿。

It rained four consecutive days.
连续下了四天雨。

Four tickets for the gallery, please.
请给我四张顶层楼座的票。

stage是什么意思：
n. 阶段；舞台；演员的职业；事件发生地；站，架，层；上演
v. 上演；举行；展现；筹划

As the elapse of time, their feeling warms up stage by stage.
随着时间的推移，他们的感情逐步升温。

stage well [Badly]
很[不]适于上演

She was mad about the stage.
她狂热地迷恋着舞台生活。

This theatre has a revolving stage.
这家戏院的舞台是旋转式的。

The novel is being arranged for the stage.
正在改编小说使适宜于上演。