something that is essential before you can achieve sth else
1.必要条件[资格]
1.a condition that must exist before something can happen
1.All this, he writes, "began with water, the sine qua non of any civilization. "
他写道，所有这些，“来源于水，水是任何文明产生的必不可少的条件。”
2.You could say that the very sine qua non of UNIX and Linux programming is writing code to deal with files.
您可以认为，UNIX和Linux编程实际上是编写处理各种文件的代码。
3.He soon found that freedom from fear of arrest was not the sine qua non of his existence.
他很快就发现，消除对被捕的恐惧，并不是他生存的必要条件。
4.It would have been the right thing to do: restarting growth is a sine qua non for ending the eurozone's crisis.
降低利率本来应该是正确之举：重启经济增长是结束欧元区危机的必要条件。
5.These rights are the basis of a civilized modern society and the sine qua non of democratic politics.
这些权利是现代文明社会的基础也是民主政治的最起码的前提。
6.But voters' ability to throw the rascals out at regular intervals is still the indispensable sine qua non.
不过，选民能够定期摒弃一些流氓无赖的能力仍是不可或缺的必要条件。
7.Mr Erdogan sees an Israeli-Palestinian settlement as the sine qua non of strategic stability in Turkey's back yard.
埃尔多安把以巴和解看作土耳其后院战略稳定的必要条件。
8.Economic justice is the basic platform, moral justice the value basis, and political and legal justice the sine qua non.
政治、法律公正是公正的必要条件，经济公正是公正的基础性平台，道德公正是公正的价值基础。
9.Because it's hollow. it weighs very little. thereby creating that sine qua non of the building world: something strong but light.
因为竹子是空心的。它重量轻。因此竹子满足了是建筑世界的必要条件。强度大。但重量轻。
10.There are others, of course, but better roads and airports are the sine qua non for catching up with China.
当然还有其它因素，但改善公路和机场则是赶上中国的必要条件。