One of the requirements for a fire is that the material _______ to its burning temperature.
A、is heated
B、be heated
C、will be heated
D、has been heated
【正确答案】：B
【题目解析】：本题考查虚拟语气。一想要(desire)二宁愿(prefer)三命令(order,command)四建议(advice,suggest,propose,etc.)五要求(demand,require,request,requirement,insist,etc.)中，无论主句为何种时态，从句的谓语动词都用"should+动词原形"或只用“动词原形”。这里，material与heat之间是动宾关系，从句要用被动语态，即(should)be heatedo答案为B。
