这是一个虚拟语气句型。含义是"不是我不这么做,而是我没办法做"。虚拟语气中说"如果我能的话"要用"if I could",表示事实上"I can't"。 1. I would if I could, but I can't go with you. 如果我能的话我会的,但是我不能跟你去。 2. I would if I could, but I really have no idea. 如果我能的话我会的,但我真的不知道。 3. I would if I could, but I have to say sorry. 我不得不跟你说抱歉。如果我能的话我一定会的。 A: Please switch work shifts with me. 我请你跟我换班。 B: I would if I could. 假如我能的话,我会的。 A: Why can't you? 你为什么不能? B: Because I have other obligations. 因为我还有另外的职责。