Subtyping
v. 子类型化（subtype的现在分词）
🗣️ 情景例句
Alexandra.
Alexandra。
Don't worry he wiil bring something.
不要担心他会带来什么。
Then, instead of having someone answering the phone all day, people can ring up the railway station and listen to a tape recording of the information.
然后，人们可以打电话到火车站，从录音电话中获取信息，而不要安排一个专人整天接电话。