<p>I think practice tests are a good idea. But if you don’t already have a good handle on English prose, the amount they will help you is limited. I think to do really well, you should be able to say frequently, “I know this is wrong because you just wouldn’t say this in English.” Even if you can’t explain the rule. I don’t know any other way of achieving that level of comprehension other than a lot of reading. Again, looking at the first example above, I don’t know of any rule that says why “calibrated” is wrong in that sentence. It just is. Or, at least, “sensitive” is obviously more right.</p>