你什么时候意识到它是有害的?
When did you realize that it was harmful?
【分析】When did you realize that it was harmful?
【解答】这是特殊疑问句.询问"什么时候"疑问词用when;询问过去的事,用一般过去时,助动词用did,助动词提前,谓语动词用原形;主语是you;动词是realize,表示"意识到";后面用that引导宾语从句,主句一般过去时,从句也是一般过去时.从句的主语是it;主系表结构,be动词用was,"有害的"用harmful,形容词作表语.
【点评】此题考查汉译英,在熟知每个汉语的英语翻译的基础上,根据语法结构,组合短语或者句子,便可得出正确答案.