… could have V-ed …

结构︰

主语＋could have＋过去分词

说明︰

此句型意为“原本能够…但却未如此”。

He could have bought the car, but soon his company went bankrupt.
他本来能买那辆车的，但没多久他的公司就倒闭了。
He could have finished it on schedule, but somehow he fell behind.
他原本能按预定进度做完这件事的，但不知怎地却落后了。
I could have done it if I had wanted to.
如果我那时想做，我能做得到的。