bring about 和 come about 都有“发生”的意思吧 有什么区别?

bring about 和 come about 都有“发生”的意思吧 有什么区别?
用法上

在字面上bring about约等于cause,有主动的意思,而come about约等于happen\occur,有被动的意思.
从以下的例句可见一斑：
有关bring about：
The goal of retting is to bring about decomposition of the pectin.
浸渍的目的就是在于使果胶质分解.
My endeavors to bring about a settlement were ended in vain.
我想达成和解的努力均归徒然.
The Liberals wish to bring about changes in the electoral system.
自由党人想要改变选举制度.
The programs for European economic recovery were expected to bring about lasting prosperity.
恢复欧洲经济的各种计划,都是为了带来持久的繁荣.
Microorganisms are the agents that bring about the chemical change.
微生物是引起化学变化的作用者.
The move stopped the pound's decline but failed to bring about a significant rally.
该行动止住了英镑的下跌,但是未能使比价有很大上升.
These butylraidicals bring about a rapid polymerization of styrene.
这些丁基自由基促使苯乙烯聚合速度加快.
They were going to try to help bring about a rapid solution of the war.
他们将设法促使战争得以迅速解决.
有关 come about
How did it come about that he knew where we were?
他是怎麽知道我们在什麽地方的呢?
Come about 4 o'clock.We'll have cocktails and grill steaks.
请四点钟左右来,我们喝鸡尾酒,吃烤牛排.
How did this dangerous state of affairs come about
这种危险的事态是怎么发生的?
Many a quarrel as come about through a misunderstanding.
许多争执都是由于误会产生的.
The wind has come about into the north.
风向已转北.
How did all this come about?
这一切是如何发生的?
Internalization may also come about spontaneously by the merger of two units inflicting large externalities upon one another.
当两个有着巨大的相互冲突的外差因素的单位合并时,内部化也可能自发地产生.