Contratest
a. 对照试验的
🗣️ 情景例句
Fifteen minutes! Thank you. Good-bye.
十五分钟 ！谢谢 。再见。
I asked him to go to the store, but he wouldn't
我请他去商店，但是他不肯。
But the market prices are changing frequently.
但是市场价格随时都在变化。