If only位于句首引起的感叹句用虚拟语气,动词用一般过去时表示目前的愿望,用过去完成时表示过去的愿望,用would或could表示将来。
If only he knew the answer.他要是知道答案就好了。(用过去时表示现在)
If only I could speak several foreign languages!我要是能讲几种外语就好了!(用wouldcould表示将来)
If only you had told me the truth before. 要是你以前告诉我真相就好了。(用过去完成时表示过去)
注意:if only和wish的用法相同,表示的意愿也基本相同。
If only it would rain.但愿天能下点儿雨!= How I wish it would rain.
If only I had known her earlier!要是我早点儿认识她就好了!= I wish I had known her earlier.