The meaning of “的” 我费好大劲才弄懂的事情，他一下子就掌握了要领。 Does it emphasize the verb? Is it okay to omit the “的” here?

The function of “的” 哪种方法计算的北极面积最大？ Does it emphasize the verb 计算？

Modifying a noun I know that I can say： 有机会用电脑；can I say 有用电脑的机会？ as in： 如果近期你有机会去波斯湾旅行的话，你将很幸运地亲眼看到被人们称为“沙漠绿洲”的沙漠温室； can I say 你有去波斯湾旅行的机会？

The difference between 開く（あく）、開ける（あける）、開く（ひらく） Can you explain what are the differences between these 3 verbs?

来，以便 and 以 Can you explain the difference between these 3 words when referring to “in order to“？ 例子：然后在煤上烤肉以保证更好的口感。 可不可以用“来”代替“以”吗？

The meaning of “所处” 与自己所处的现在促膝长谈。 What does 所处的 mean？

“了” question 钉子很容易被刺进墙或者木头里面去了。 Why “了” is used here. I know that “了” refers to something that has been done, however “了” still confuses me a lot.

Meaning of 了 There is a book called ”请你帮我杀了她“。 How do you translate the 了 in this sentence？

The meaning of 的 My sentence：而在水质较好的城市，人们可以放心的饮用自来水。 Does 的 emphasize the verb 可以放心 before it or something？