问题补充：
Since the baby milk powder was found to be polluted, there has been universal doubt other food products are safe .
A. that; to eat
B. whether; to be eaten
C. whether; to eat
D. that; to be eaten
答案：
A. that; to eat
B. whether; to be eaten
(答案→)C. whether; to eat
D. that; to be eaten
解析：本题中的名词doubt后面是一个同位语从句，因为前面的doubt用语肯定句中，所以使用whether引导该同位语从句，表示不确定的事情。第二空使用不定式to eat对句子的主语other food进行补充说明。因为safe是对主语的性质特征进行的说明，故使用不定式的主动语态。如：The problem is easy to solve。这个问题很容易解决。句义：既然婴儿奶粉被发现已经被污染了，很多人都怀疑其他的食物是否可以安全食用。故C正确。
