单选题 O'Neal works hard. He is often seen ______ heavily before his teammates start.
A. sweated B. to be sweated C. sweating D. being sweated

【正确答案】 C

【答案解析】本题考查的是感官动词的用法。be seen to do；be seen doing“被看到做某事”。句中He与sweat是主动关系，所以用主动。本句的意思是：“奥尼尔工作非常努力。经常有人看见他在队友开始训练前就辛苦地练习了。”