She was just about to explain she hadnt passed her maths test chiefly out of carelessnes

问题补充：

She was just about to explain she hadn passed her maths test chiefly out of carelessness her uncle came.

A. her mother … when

B. to her mother why … that

C. her mother that … when

D. to her mother that … when

答案：

A. her mother … when

B. to her mother why … that

C. her mother that … when

D. to her mother that … when

解析：explain/ announce等后面的结构是～ sth. to sb.或～ to sb. sth.，to 不可省略。