after all 和 only if 的用法

after all 毕竟
. You should forgive him for his forgetfulness; after all, he is over seventy.
你应该原谅他的健忘症，毕竟他已经七十多岁了。

2. You should be charitable with him; he is a child after all.
你应该对他宽容些，毕竟他还是个孩子。

3 Don't blame him for breaking that vase; after all he is a child.
别怪他打碎那个花瓶, 他毕竟是小孩子嘛。

only if:
只有当(只是在...的时候)

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。

after all
有两个意思
a. 毕竟，终究，归根结底。
例句：1。So you've come after all.你到底还是来了
2。After all, what does it matter?归根结底，那有什么关系呢？
b.应该记住
例句：He shoul