Premise:
"China may have improved since 1979, but it still has an unblemished history of authoritarianism, five millenniums without sustained democracy.)"
Hypothesis: The rapid improvements in China since 1979 mean that it will soon embrace democracy.

it is not possible to tell

Premise:
"The Water Quality Initiative"
Hypothesis: No one is focused on water quality.

no

Premise:
"She jerked her head, and a thick braid flopped from under her wide-brimmed hat."
Hypothesis: From under her wide-brimmed hat a thick braid flopped.
yes