In those days, we had no phones, so we have to keep in touch _________ writing often

The terrible disease, ______ already kills about one million people each year, has grown resistant ______ standard medicine..

A survey indicates the _____ of men to women in the population has changed in recent years.

Lily, Your task is _______ when the train will leave.—Ok, I’ll do it right away.

You got second and Tim first in the race! How did Tim beat you——________ Maybe he is just a lucky dog!