The questions and answers for all endorsements are free and online. At the top of page click on “Useful links”. You can also Google “practice tests” and “Trucker Country”.
I used to administer tests to future pilots. Here is the easiest way to pass these tests: read the question and then read ONLY THE CORRECT ANSWER. Do NOT read all of the possible answers. At the Trucker Country website take a test, but do not answer any question. When you click to get your score, it will show you the correct answers. Do NOT think the test is asking about real life. Do not get into a “what-if” discussion about the question. Just read the question and then the answer. Do it for maybe 20 minutes then take a break. Go at your own pace. Do all tests on each endorsement until you are scoring 90% and then practice on your next endorsement.
The key is you want to be familiar with the question and then recognize the answer. Reading the question should trigger some key phrase of the answer once you have practiced enough. The goal of the paper or computer test is to pass it. Give them the answer they want and don’t expect to learn real-life ingo from the test.