Question

Fill in the blank with a suitable adverb clause:
No other scientist can be .

• A. as modest as Einstein
  
• B. a great one
  
• C. as rare
• D. None of the above

Answer 1

Answer: (A)

as modest as Einstein

An adverb clause is a group of words containing a subject and a verb, and it functions as an adverb, by modifying an adjective, verb or an adverb. Adverb clauses generally begin with a subordinate conjunction (since, because, while, etc.)
Option A is correct because it is an adverb clause of comparison, 'as modest as' compares to the 'likeness of'. In 'as modest as', the first 'as' is an adverb that modifies the adjective 'modest'; the second 'as' functions as a conjunction, followed by a clause: Einstein (is).
(In comparison sentences, the subordinate clause is usually elliptical (an elliptical sentence has words missing because they have already been implied before). Hence 'Einstein' is an elliptical clause.)
Option B is incorrect because it is a phrase, not a clause. (A phrase is a group of words that do not have a complete thought, they lack the subject or verb, or both, that would make it a clause. A phrase is a part of a clause.)
Similarly, option C is incorrect because it is a phrase, not a clause.
Option D is incorrect because the answer lies in A.