为什么在编译为sql时，EF 5.0不支持这种EF 4.x LINQ语法？

I have some code that was recently upgraded from EF 4.2 to EF 5.0 (actually EF 4.4 since I am running on .Net 4.0). I have discovered that I had to change the syntax of my query, and I'm curious as to why. Let me start off with the problem.I have some code that was recently upgraded fro