second: choose a stable space
The first point:
optimization ranking website, stable space is to make Shanghai the first choice for trust love. Love Shanghai every day in the spider crawling countless websites, when the love of spiders in Shanghai come to your website and found the website is not open, this is not very friendly to love Shanghai spiders, and when the first spider web site is not open, second times to the website can be opened, then back and not open so, again, love of spiders in Shanghai will also have temper, finally may not return your website. As we humans also have temper, not again and again three. After all, we often say that "three strikes". The actual is the same reason.