1. If you are going to speak in public you should learn how to use hand gestures in public speaking.2. I gave the speaker a hand signal while I was leaving.3. I made a thumbs-up gesture to my son when he reached the finish line.
 hand signal hand sign hand gesture注意: 用 make a hand gesture to somebody 而不是 give a hand gesture to somebody.
Team A's defeat over Team B is considered the biggest undrdog victory in basketball history.