Answer:
The adverb clause in the sentence We're moving to Abilene if we sell our house is if we sell our house.
Step-by-step explanation:
An adverb clause is a dependent clause that plays the role of an adverb to modify an adjective, a verb or another adverb and that, as any other clause, includes at least one subject and one verb. Adverb clauses are grouped according to what they modify, such as place, purpose, time, cause, condition and more.
In the case of the sentence We're moving to Abilene if we sell our house , the adverb clause if we sell our house is introduced by if and, as a whole, modifies the verb moving.