第12题: [单项选择]We ______ our breakfast when an old man came to the door. A. just have had B. just had C. have just had D. had just had 参考答案:D 答案解析:[解析] 本题测试的是动词时态的用法。关键在于了解just的用法，一般与完成时连用且放在助动词与实义动词之间使用。因此本题答案为D。
第15题: [单项选择]There are ______ incurables; there are only things for which we have not found a cure. A. no such a thing as B. not such a thing as C. not such things as D. no such things as 参考答案:D 答案解析:此题考查存在句式主谓一致的问题。由于题干的系动词为复数，因此只能在C项和D项之间进行选择。C项not为一般的否定副词，而D项no为其强化的形式，相当于not any，表示与所说的事截然相反，意为“绝没
第16题: [名词解释]热通道因子 hot channel factor 参考答案:考虑核的和工程的各种不利因素后，热通道中反应堆冷却剂的比焓升或轴向平均热流密度与相应的堆芯平均比焓升或平均热流密度的比值。
