my teacher didn't tell me directly I still felt that I didn't live up to her expectation

问题补充：

my teacher didn tell me directly, I still felt that I didn live up to her expectation.

A. When

B. Since

C. As

D. While

答案：

A. When

B. Since

C. As

(答案→)D. While

解析：D考察连词。句义：虽然老师没有直接告诉我，但是我仍然感觉到辜负了她的期望。While在本句中作为连词，意为：虽然；when既然，当…时；since因为，由于；as因为，随着；根据语境可知D正确。