Question

7. It was several minutes    we realized what was happening―our dog was trapped in a newly dug tunnel.

A. since   B. before

C. until   D. while

Answer 1

7.    B考查状语从句的连接词。句意：过了几分钟我们才意识到发生了什么——我们的狗被困在新挖的隧道里了。这里使用了句型"It was+—段时间+ befor^..""要多久之后才/就……"，所以选B。