Premise:
"No, we must look elsewhere. "
Hypothesis: There are a few places left to check.

it is not possible to tell

Premise:
"They are well observed, well written, and remote, and no more than a handful, if that, will last."
Hypothesis: They bring little intelligence to the works.

no

Premise:
"I'd made my plan whilst I was waiting for her."
Hypothesis: I couldn't conceive of a plan, no matter how hard I tried.
no