世态炎凉的英文：
the fickleness of the world; inconstancy of human relationships

参考例句：

Laugh and the world laughs with you, wrap and you weep alone.
笑时万众附和，哭时独自垂泪（世态炎凉）。

Fickleness of human friendships
世态炎凉

fickleness是什么意思：
n. 浮躁;变化无常

Fluctuating prices usually base on a fickle public's demand.
物价的波动往往是由于群众需求的不稳定而引起的。

feeling of doubt, fickleness uncertainty, and fear of loss often accompany infatuation.
疑虑，花心，不确定和对失落的恐惧常与迷恋如影随形。

As for independents wavering most, unattached voters are naturally more fickle than loyalists.
至于波动最大的独立选民，他们本来就比忠诚的支持者易变。

world是什么意思：
n. 世界；宇宙；领域；世人；人世；天体，星球

This may be normal in the physical world, but there is no reason for it in the world of software.
在物理世界这是正常的，但没有理由在软件世界也这样。

They wanted to revolutionize the whole world.
他们要在全世界发动革命。

That are inexorably shaping the world of tomorrow.
这将无情地影响明日的世界。

inconstancy是什么意思：
n. 易变,不定性,无节操,反复无常

Modern character is inconstant, divided, vacillating
现代人的个性是无常的，分裂的，摇摆不定的。

Hermia was looking at him and wondering at his strange inconstancy
赫米亚望着他，对他莫名其妙的反复无常感到很惊奇。

Well, my friend, fortune is inconstant, as the chaplain of the regiment said
唉，我的朋友，命运是变化无常的，这是那个——那个军队里的教士说的话。