if only引導的是什么從句

　　例句：

　　If only you had told me that some time ago.

　　要是你之前告訴我那件事該多好。

　　If only he'd remembered to send that letter.

　　要是他沒忘記發那封信就好了。

　　If only I could have helped put matters right.

　　要是我當時能幫著把錯誤糾正過來就好了。

　　'If only I had known you then,' he said wistfully.

　　“要是我那時認識你就好了。”他向往地說道。