He received atelegram “Mother Sick.”

15．– How cold it is! I wonder how grass survive under such heavy snow． –Don’t worry．There is a lot of air in loose snow which _______．

The passenger was tired and walked slowly but he got home____.

You should be careful when you take the chemistry exam．—I agree．In this way,1 will make mistakes．

ternational agreement, __________to help people kick off the habit of smoking, was signed two years ago.