4, It is all very well for such things to occur in fiction
 occur:  某个事件出乎意料的发生（正式）
 happen:
一个事件出乎意料发生
 take place:  事件根据安排“举行”
Eg.: When did the accident happen / occur?
It occured to me that / to do.
It occured to me to open the window.
       When will the wedding take place
 
5,  To varying degrees, we all have secrets which we do not want even our closest friends to learn
 learn: 了解某个事实，学习某种知识、技能
know: 知道某个事实，具有某方面的知识、技能，认识、了解某个人（状态动词，不能用于进行时态）
I learned that I had passed the test.
She knows about computers.
She is learning about computers.
instead of + doing----表示相反、没有、取而代之的是.......