In South Africa English is the language black parents wish their children to be educated

问题补充：

In South Africa, English is the language black parents wish their children to be educated.

A. for which

B. that

C. in which

D. when

答案：

A. for which

B. that

(答案→)C. in which

D. when

解析：C 考察定语从句。本句先行词是the language，定语从句句子结构完整，说明先行词在定语从句做状语。因为be educated in在…方面被教育，为固定搭配。所以使用in which引导定语从句。故C正确。