The opportunity was perfect, so I did not think twice before accepting the job.

did 是 do 的过去式，表示"做"的动作。 not 是否定词，表示"不"。 think 是动词，意思是"思考、考虑"。 twice 是副词，意思是"两次"。 did not think twice 是一个固定短语，字面意思是"没有思考两次"，引申为"毫不犹豫"的意思。