The answer was explained in the preceding paragraph.
答案在前一段已经作了解释。
Take an expression with you
This preview contains only public teaching examples or a lesson summary. It excludes your responses, notes, learning history and identity, and is not sent automatically.
Content is internally reviewed; independent language review is pending.
Read the complete entry or lesson — no registration needed · Source and version
You can also select the text and copy it manually. Links printed in a PNG are not clickable; include the text link when sending.