单选题 One of the requirements for a fire is that the material ______ to its burning temperature.
A. heated B. be heated
C. to be heated D. being heated

【正确答案】 B
【答案解析】[解析] 本题测试虚拟语气。名词requirement的同位语从句或表语从句的谓语需用虚拟语气should+动词原形。