crater floor

例句：

1. 1. The astronauts landed on the moon's surface and examined the crater floor.
   宇航员们在月球表面着陆，检查了坑底。
2. 2. The geologist found evidence of ancient volcanic activity in the crater floor.
   地质学家在坑底发现了古代火山活动的遗迹。
3. 3. The scientists conducted tests on the crater floor to determine its composition.
   科学家们对坑底进行了测试，以确定其成分。