【题目】Parents should set a good example to their children by being in exercise and keeping fit.
A.awake
B.active
C.alike
D.alone

【答案】B
【解析】be active in...意为“在莫方面积极”。句意：家中应该通过积极锻炼保持健康给子女树立好的榜样。根据句意选B项。