In this task, you are given a sentence and question which can be answered using the sentence. Your task is to answer the question using the information from the sentence. The answer to the question is unique and it is a continuous text span from the sentence.

Sentence: Instead , much of numerical analysis is concerned with obtaining approximate solutions while maintaining reasonable bounds on errors . 
 Question: what is  concerned?
much of numerical analysis

Sentence: In addition , even when they do match , escape mutants are often generated . 
 Question: what is  generated?
escape mutants

Sentence: However , when compared to BLAST , it is more time consuming , not to mention that it requires large amounts of computer usage and space . 
 Question: what   requires something?

it