only if/if only分别是什么意思？

only if/if only分别是什么意思？

if only: 要是...多好

Examples:
1. If only he had been here.
要是他当时在这儿就好了。
2. I dread the coming exams. If only I could have time to review my lessons.
我对即将到来的考试非常担心。如果我有时间复习该有多好啊。
3. If only I had another chance.
要是我再有一次机会就好了。
4. I am so tired. If only I can take the day off tomorrow.
太疲倦了。如果明天能不上班多好。
5. If only problems would come one at a time!
要是问题一次只发生一个该多好！
6. If only it clears up, we'll go.
只要天一放晴,我们就去。
7. If only one had an unlimited supply of money!
要是财源不断就好了！
8. She would be a very good player if only she could get it together.
她若能控制得当就能成为很好的选手.

only if:
conj. 只有当(只是在...的时候)

Examples:
1. The company will succeed only if it have sufficient backing.
只有当该公司获得足够的资助，它才会成功。
2. A compound proposition that has components joined by the word and or its symbol and is true only if both or all the components are true.
综合命题由和或其符号所连接的子句组成的复合命题，只有当所有子句为真时，该句才为真
3. I can buy the house only if a mortgage for 2000 dollars is available.
只有拿到两千美元的抵押贷款，我才买得起那栋房子。
4. Only if I get a job will I have enough money to go to school.
我只有找到了工作才有足够的钱上学。

If only 用在虚拟语气中，如 If only I could go on vacation in Hanan. 意思就是：如果我能去海南渡假就好了。 Only if 用在条件状语从句中，表示“只有…才…”的意思，如：Only if you study harder can you make progress in your study. 它放在句前要倒装。

only if

只要……就；只是在……的时候

if only

只要；要是…多好