I'll take care of you,that's my plan.这里的that's为什么不用this is?

I'll take care of you,that's my plan.这里的that's为什么不用this is?
I'll take care of you,that's my plan.
这里的that's为什么不用this is?

I'll take care of you,that's my plan.这里的that's为什么不用this is?
this is是中式的解释.