[Bad print of layers]

This layer is supposed to be all solid. But it gave a very bad print. Anyone knows why this happen?

[filament is stuck in the feeder end]

I tried the function of insert material. It seems ok when I insert PLA and the nozzle works fine. But when I started to print things, the material gets stuck and totally grounds down. I assume that is why the material fails to move forward.

I get the wire out by "move material". Here is the pic of the PLA wire:

Anybody has the same problem as me?