Question

Whatever the cause of the heat may be, we do know that the earth gets hotter ________ down we dig．

1. A.
   further
2. B.
   the farther
3. C.
   the farthest
4. D.
   the furthest

Answer 1

B
考查形容词/副词比较等级的的常用句型的运用。此处是the more…, the more…的句型的变式。The farther we dig是表条件的分句，相当于if we did farther。句意：无论地热的原因是什么，我们确实知道，如果往下挖得越深，地球会变得越热。