Only in this way, can you learn English well.
Only after being asked three times did he come to the meeting.
如果句子为主从复合句，则主句倒装，从句不倒装
Only when he is seriously ill, does he ever stay in bed.
1) 表示允许或请求;表示没有把握的推测;may 放在句首，表示祝愿。
May God bless you!
He might be at home.
注意： might 表示推测时，不表示时态。只是可能性比may 小。
2) 成语： may/might as well，后面接不带to 的不定式，意为"不妨"。
If that is the case, we may as well try.
典型例题
Peter ___come with us tonight, but he isn‘t very sure yet.
A. must B. may C. can D. will
答案B. 表可能性只能用may. 此句意可从后半句推出。
From:https://www.zgghmh.com/CET-6/20004526.asp