--- Measures must be taken to stop factories from wasting energy in course of production. ---___. The energy is becoming scarce day by day.
______ to reach them on the phone, we sent an email instead.
Our bodies are strengthened by taking exercise. ______, our minds are developed by learning.
American Indians ______ about five percent of the U.S. population.
The problem of global warming is serious. ______, the sea levels have risen a little.
At the beginning of class, the noise of desks ______ could be heard outside the classroom.