Thanks for reply!
Here my version is 0.2.0_1,and the problem still exists.
My computer doesn’t have GPU,so I just try the code with the cpu version
Do you have some advises?
= = =
I have tried 2 machines:

Computer A without GPU and install CPU version 0.2.0_3
Computer B with GPU and install GPU version 0.2.0_3
Then I run the codes above,and here is the result:
In computer A, the error reappears every time( after every reinstall)
In computer B, I try the code with.cuda() and without ```.cuda()````, and the error vanishes,and the code runs normally.

So I think it is a bug in CPU version with a no-GPU computer ,which needs to be fixed.