题目：
The firm should make a substantial profit satisfactory labor relations are maintained.
A．in case
B．with the purpose that
C．provided that
D．even if
答案：
参考答案：C
解析：四个选项都是起从属连词作用的词或短语，因此答题的关键是分析前后两个句子的逻辑关系。in case和with the purpose that引导目的状语从句；even if引导让步从句；而provided that引导条件从句，正好符合该句句意。
