how to keep the phrase when I delete the charactor of the abbrev?

[imleg...@gmail.com]

Here is the thing. 

I have a phrase which abbrev is 'ck'. ck is for check. 

When I type ck and space, check shows out is ok, when I type backspace at this time, the check disappear and change to ck which I dont want. I just want the check keep, dont change back to ck so how to solve this question

I already check the flags in the abbrev setting seems no flags related to this issue, anyway to solve it?