I was leaving the office when it suddenly 　　　 to me that I had forgotten my keys.A. struck

问题补充：

I was leaving the office when it suddenly to me that I had forgotten my keys.

A. struck

B. happened

C. occurred

D. hit

答案：

A. struck

B. happened

(答案→)C. occurred

D. hit

解析：考查固定句式。固定句式：sth occur to sb某人突然想起某事；本句中的it是形式主语，主旨的主语是后面的主语从句that I had forgotten my keys.句意：我正要离开办公室，在这时我突然想起我忘记带钥匙了。故C正确。