Grandpa is old, but he is still very ____.

 —Were you all frightened at the sound of the fire alarm?— No. Everyone stayed _______ and obeyed the police.

Once harm is _______ to the eco-system, all species will ________, including man himself. 

With April 18’s railway speedup, highway and air transport will have to compete with ________ service for passengers. 

It was _____ of Jack to turn off the radio when I was sleeping in the bedroom.