Work gets done _______ when people do it together,and the rewards are higher too.

Once people have seen something actually happens, they are much more_______to accept the change.

Attention, please! And keep ________ when I am taking a photograph of you.

   Don’t touch the ____ wire. It’s dangerous.

Compared with his sister, Jerry is even more ____   to, and more easily troubled by , emotional and relationship problems.