Question

Which sentence has an elliptical adverb clause with an understood word or words?

As we travel higher than does the sea level, the boiling point of water drops.
Methyl alcohol boils at a lower temperature than water.
Water turns into ice when the temperature is lowered to 32°F

Answer 1

As we travel higher than does the sea level, the boiling point of water drops.

Answer 2

The answer is indeed "As we travel higher than does the sea level, the boiling point of water drops."

Step-by-step explanation:

An elliptical adverb clause is a dependent clause that presents one or more words implied. This type of clause functions as an adverb, modifying verbs, adjectives, or other adverbs.

In the first option, the sentence "As we travel higher than does the sea level, the boiling point of water drops" presents as its elliptical adverb clause the structure "than does the sea level". The implied word here is the verb "travel". It was omitted to avoid its repetition. If it hadn't been implied, the structure would be "than the sea level travels". This clause is modifying the adjective higher. Thus, we have an elliptical adverb clause.