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(hào)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(shí)，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(huì)成功。