单选题 She became angrier as the years went on because she saw that they were doing to other youngsters.
A. angrier
B. on
C. that
D. other

【正确答案】 C

【答案解析】应改为what。what既是saw的宾语，又是从句中doing的宾语，表示“所……的”，而that没有这种用法。