【题目】We should do what we can ______ people's hard work pays off.
A.be sure
B.being sure
C.making sure
D.to make sure

【答案】D
【解析】考查非谓语动词 。句意：我们应该做我们所能做来确保人们的努力得到回报，不定式用来表示目的，故选D项。