Our ability to think and speak makes us (difference) ______ from other animals.

A．Because he hasn’t a phone.
B．Because he’s leaving the city right now.
C．Because he’s calling from a friend’s.
D．Because his wife is terribly sick.

A．Because she was worried about the birthday party.
B．Because she found this history course very challenging.
C．Because she thought her term paper might be late.
D．Because she had a very hard time sleeping.