As a result, lvalues can be used in more contexts than can rvalues.
结果，可以使用左值的上下文比右值更广。
2
If you get this warning, examine your code to see if it depends on binding rvalues to non-const references.
如果接到这项警告，请检查您的程序码，查看是否依系结右值至非常数参考而产生。
3
Variables are lvalues and so may appear on the left-hand side of an assignment. Numeric literals are rvalues and so may not be assigned. Given the variables.