Jim _______ ride to school. But now he _______ walking to school because he wants to keep fit.

The microphone enabled them to keep in touch, in other words, it made it _____ for them to contact each other.

When the building burns, the firemen will arrive at once and the fire.

________ , the polluted air canresult in deadly diseases or even death

Will you go skiing with me this winter vacation—It ______.