but only

基本解释

But only when they have confidence that they can recover this state can people be truly courageous in what they do.
但是，仅仅是当他们有信心他们能够恢复到这个状态时，人们才会真的有勇气这样做。
You will have many Activities for the project, but only one Task and one Request.
您将拥有许多这个项目的活动，但是只有一个任务和一个请求。
But only the fortunate few can say that.
但是，只有少数的幸运儿可以这样说。

People can also cause a blockage when they try to clean out their ears, but only push the wax deeper inside.
So both of these stories involve floating point values, but only in this case am I actually allocating memory.
所以这两个故事都涉及到浮点类型，但是只有那样我们才能真正地分配到内存。
哈佛公开课 - 计算机科学课程节选
So the open curly brace followed by the closed curly brace means everything inside of these curly braces should get executed, but only if that first condition is actually true.
所以左花括号后面跟着,右花括号，这意味着花括号里面所有的代码,都应该是要被执行的，但只有当第一个条件是正确的。
哈佛公开课 - 计算机科学课程节选

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