duck soup = easy, effortless
容易，不需付出什么努力，小菜一碟

范例对话:
A: Can you help me hook up my new stereo equipment? I'm having quite a bit of trouble with all these connections.
你能帮我将立体声音响的电源机上吗？我连这些连接有点问题。

B: Sure. That's duck soup for me.
好的，那对我来说小菜一碟。

A: Well, with all your experience in electronics, I have no doubt that it will be very easy for you to do.
是的，你在电子方面有丰富的经验，对你来说很容易，对此我毫无疑问。

B: No problem. Glad to help out.
没问题。乐意效劳。