After several tries, I got past star 4 of C#. I noticed, though, that there were some questions that were dubious. I don't know if the question writers were trying to be deliberately tricky or there's a C# standard out there that's different from Visual Studio's, or it could be that I am missing something.
For instance, one of the questions asked me to identify which of the choices was NOT among the common methods inherited by all classes from the object class. The thing is, all of them were among the common methods (according to the notes!). The exception was a method that was misspelled--Equal instead of Equals, with an "s".
Another similar problem cropped up when the question asked which of the choices was not a method of the string class. All the choices were methods, with the exception of Copy. There was a CopyTo method, but not a Copy without the To (again, as far as I could tell...).
Finally, there was a question asking what exception is thrown when you attempt to use an uninitialized object. As far as I could tell, this won't even compile. Again, unless I didn't understand the question.
These were the three questions that mystified me, especially the third one. As I said, I'm not sure if these were trick questions or what.