如果你碰巧见到彼得,代我向他问好。
If you ___happen ___to see Peter, say "hi" for me.
你该不会正好知道她的电话号码吧?
You don't ___happen ___to know her phone number, do you?
我现在能理解我偶然读到的任何英文内容。
I can understand whatever I ___happen ___to read in English now.