I can not preview my survey

Hello xiaoyankai,

I'm sorry for the trouble caused to you. 

I did test your form and I am unable to replicate the issue you are having. Your form loaded just fine in browser and I was able to view it without any problem. Please check the screenshot below:

Is there any firewall which is blocking the access to your form?  I would suggest you to please use the following form URL and see if this works fine: 

https://www.jotform.com/71971024155453  

or 

https://www.jotformpro.com/71971024155453

Do get back to us if the issue persists.

Thank you!