Problems with request. querystring []

For the relationship between the table structure, the Chinese parameter data needs to be transmitted in the URL. The problem is as follows:

1. http: // localhost/test. aspx? Lanmu = "book", using request. querystring ["lanmu"], obtained "book, not" book ";

2. http: // localhost/test. aspx? Lanmu = book, use request. querystring ["lanmu"], get a null value;

3. http: // localhost/test. aspx? Lanmu = book. Use request. querystring ["lanmu"] to obtain the correct value Book;

The rules I have summarized are as follows:

If the Chinese characters contain even data (including fullwidth symbols );

The value can be obtained normally. If it is an odd number, it can only be an even number (odd-1 and the odd number is not 1;

If it is a Chinese character, the null value is obtained;

Which one can explain why and how to get the correct value.