Question

Life is like riding a bicycle. ________ your balance, you must keep moving.

A．Keeping	B．To keep
C．Keep	D．Being kept

Answer 1

B

B　句意：生活就像在骑自行车。为了保持平衡，你必须不断前进。根据句意可知此处需用不定式作目的状语，故选B项。