b) You can have it for a trial period.
The answer is no, period!
“What do you have next period?’ ‘French.’
c) At that instant, the door opened.
The show was a instant success.
I don’t like instant coffee!
d) Don’t desert me in my hour of need.
I can’t turn him away in this hour of night.
We’re paid by the hour.
e) I don’t think for a second that she’ll accept.
Her styles are always up to the second.
The train arrives at 9.05 to the second.