The children started planning how to spend the holiday, their lessons _____ for the term. [ ]

A. finishing

B. finished

C. had finished

D. were finishing

在实际标准化工作中，运用简化原理有两个界限：简化的必要性界限和（）。

A.简化的合法性界限

B.简化的适度性界限

C.简化的合理性界限

D.简化的适时性界限