| A | B |
|---|
| airtight | not allowing air to get in or out |
| bedrock | solid rock just beneath the earth's surface |
| casualties | deaths or serious injuries |
| comprises | consists of; includes |
| density | thickness; the amount of something in a given space |
| excavation | digging |
| immersed | completely covered by a liquid |
| impervious | incapable of being passed through or penetrated |
| laborious | requiring long, hard work |
| productive | having positive results; effective |
