重载后不再具有短路的特性，C#干脆禁止了对它们的重载，只能通过以下形式变通，居然保持了短路的语义：
class Test {
public static bool operator false(Test test){
return false;
}
public static bool operator true(Test test){
return false;
}
public static Test operator & (Test lhs, Test rhs){
return lhs;
}
public static Test operator
关键词：The C# Programming Language Notes