1 你的句子不完整,我来完善：Only if he had seen me yesterday,would he have told me to go with him.
2 你的句子是虚拟语气
3 当only修饰从句的时候, 主句必须倒装.
4 我问一下,你的句子是不是---- If only he had seen me yesterday? 或者说,你把only 和if 换了位置?
5 如果是 If only he had seen me yesterday!,你的句子就等于：How I wish he had seen me yesterday! ----------也是虚拟语气的句子.
纠结啊.