Definition: a piece of underwear that you wear under a shirt Level: C1
在这种天气里，你需要一件背心。
You'll need a ___vest in this weather.
包裹里包含一件中号的白色背心。
The package includes a medium-sized white ___vest.
他总是在衬衫下面穿一件背心来保暖。
He always wears a ___vest under his shirt to stay warm.
