Question bank for Quants:
Gmat Club is the best place to prepare for quants.
You can try GC tests for 700+ level questions, enabling you to achieve Q49-50 or perhaps Q51.
Theory: GC offers free reference theory material for quant book.
Link :
gmat-math-book-87417.htmlQuestion bank for Verbal:
Veritas has a good question bank for verbal questions. In addition to it, you can try Aristotle grail series which offers
100 Critical Reasoning Questions
100 Sentence Correction
60 Reading Comprehension passages.
Furthermore, you can purchase GMAT prep Question pack for more practice in official questions.
Hope that helps