It was not ________ she took off her dark glasses ________ I realized she was a famous film star．

A.when; that

B.until; that

C.until; when

D.when; then

答案及解析： B

解析：

该句为强调句型，原句为：I didn't realize she was a famous film star until she took off her dark glasses．被强调部分为“not until+时间”结构，强调句型的连词必须是that(指人时可以是whom)，不能是when．