副詞 only if:

1. never except when
   同義詞：only, only when

1. 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夠的錢上學(xué)。
2. I can buy the house only if a mortgage for 2000 dollars is available.
   只有拿到兩千美元的抵押貸款，我才買得起那棟房子。
3. 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.
   綜合命題由和或其符號所連接的子句組成的復(fù)合命題，只有當(dāng)所有子句為真時，該句才為真
4. The company will succeed only if it have sufficient backing.
   只有當(dāng)該公司獲得足夠的資助，它才會成功。