find whole words only

例句：

1. 1. I foundthe key under the sofa cushions.
   我在沙发垫下找到了钥匙。
2. 2. Thescientist discovered a new speciesof plant in the Amazon rainforest.
   科学家在亚马逊雨林发现了一种新的植物物种。
3. 3. He ascertained thatthe information was accurate.
   他确定信息是准确的。