jump in
　　该动词短语有两个常用的意思。第一，打断对话（to interrupt a conversation），例如：
　　Before she could reply Peter jumped in with an objection.
　　此处是第二个意思，就是不多想直奔主题（to start to do something very quickly without spending a long time thinking first）。
　　有个表达跟它感觉特别像，就是cut to the chase，它的英文解释是to stop wasting time and start talking about the most important thing。

　　trade something in
　　To give something used as part of the payment for something new.
　　He traded in his old car for a new Mercedes.
　　这个动词短语的名词形式是trade-in，表示"以旧换新"这个方法或者旧物本身（a method of buying something by giving a used item as part of the payment for a new one; the used item itself）。例如：
　　the trade-in value of a car
　　Do you have a trade-in?