Premise & hypothesis.
Boys and men, mostly all wearing helmets, hang on to two separate cars while they ride skateboards.

Boys and men are riding fast.
++++++++++
true or not.
it is not possible to tell

Premise & hypothesis.
Four teenagers having a blast in a basement playing the video game Rock Band.

Teens having fun.
++++++++++
true or not.
yes

Premise & hypothesis.
A person in dark clothes and carrying a bag is crossing the street.

A person wearing dark clothes sits at the bus stop waiting for a ride home.
++++++++++
true or not.
no