【正确答案】 1、is thought    

【答案解析】[解析] 本题考查一般现在时和被动语态。因为he是动作think的承受者，应填入被动语态be thought。同时，根据定语从句的时态为一般将来时，所以可知主句为现在状态。故应填入is thought。本题可以改写为：It is thought that he has information which will be useful to the police．
[触类旁通] 类似的表达还有be said to do sth.(据说)。如：He is said to have mastered 4 languages.(据说，他掌握了4门语言。)当然，此句可以改写为：It is said that he mastered 4 languages.