Only in this way can you solve the problem.
Only if you study hard can you pass the exam.
Only then did I realize my mistake.
二、not only...(but also)在句首时，架连接的是两个句子，常用倒装。如
Not only did we lose all our money,but we also came close to losing our lives.
Not only did he speak correctly,but he also spoke easily.
I went all the way to his home only to find hime out at a meeting.
I hurried to the post office only to find it closed.
She went home only to find her house burglarized.
四、“too...to...”结构中，表示否定意思，但在“only too...to...”结构中，only too = very，表示肯定意思。如
The patient is too weak to walk.
We are only too willing to do it for you.
I am only too delighted to accept your king invitation.
五、在“one of + 复数名词 + 定语从句”的结构中，定语从句被看作修饰复数名词，谓语要用复数。但在“the only one of + 复数名词 + 定语从句”的结构中，定语从句却被看作修饰“the only one”，谓语动词要用单数。如
This is one of the best novels that have been published in the past two years.
He was the only one of the boys who was given a prize.
She is the only one of the girls who has been to the US.
六、If only 为虚拟语气的，表示愿望或未的条件，多用于感叹句，其主句常常省略。如
If only she would marry me!
If only he had known about it!
If only you could have been here earlier that day!
If only there were forty-eighty hours in a day.