Raise a Stink(protest strongly)
Listen! Don't try to use any of your sister's clothes without asking her first. She's liable to think if she finds something missing.
I'm sure that there will be no problem. She's borrowed some of my things before, and I've never said anything. I really doubt that she will protest very strongly.
doubt that ~ = ~ であるまいと疑う､ suspect that ~ = ~ であろうと疑う
I doubt that he did it. <> I suspect that he did it.