only在句首倒装的情况.例如：
Only in this way, can you learn English well. 只有这样,你才能学好英语.
Only after being asked three times did he come to the meeting. 叫了三次,他才来参加会议.
如果句子为主从复合句,则主句倒装,从句不倒装.例如：
Only when he is seriously ill does he ever stay in bed. 病得狠重时,他才卧床休息.