One of  the best online test preparation system available is this collection of ACT, SAT and GED practice tests:

http://www.freetestprep.com/category.php

(Also see: http://www.actstudent.org/sampletest/english/eng_02.html )

We have practice quizzes for these major tests that you can do whenever and wherever you want, all free of charge. Each and every practice question has an in-depth video explanation by an expert test preparation tutor who will show you how to do the test questions you missed. Our sample ACT, SAT and GED practice problems are designed to be as tough or tougher than the test questions on the actual ACT, SAT and GED exams so that you will have no surprises on test day.

On this site, users begin practicing for their upcoming test by picking the section of the ACT, SAT or GED on which they have the most trouble, and complete a practice quiz. After they finish one of the practice tests, the questions you missed will come up and you can click them for the correct answer and a video to show the student how to think through the problem correctly.

RECOMMENDED READING:  English and Reading Workout for the ACT includes:
• Practice passages and questions based on real ACT exams
• 3 English practice tests and 4 Reading practice tests, all with detailed answer explanations
• Targeted advice from our ACT experts, including how to use our 5-Step Basic Approach to master tricky sentence structure and punctuation questions
• Guidance for seeing through camouflage and acing the Reading passages

English and Reading Workout for the ACT contains all the information you’ll need to learn where your weaknesses lie—and how to overcome them.