Originally Posted by jiejie

2) If the visa has "enter before" than that is the last day (actually the day before to be on the safe side) that you may enter, and your duration of stay will be whatever the terms of your visa states. Example: My current visa has an "enter before April 3, 2010" on it, with a duration of stay of 90 days each entry. I entered China last on February 26, 2010, and I must leave the country by May 27, 2010. If I left China this month, I could re-enter on April 2, and reset the clock another 90 days from then. Then it's leave the country and new visa time. (Many of the visas, especially the 12-month multiple entries, are being issued to US citizens in the US using this terminology.)