【正确答案】 C

【答案解析】deadly：致命的。fatal：致命的。His illness was fatal to our plans, i. e. , it caused them to fail．他的病对我们的计划是致命的，也就是说，使我们的计划落空了。contagious：传染性的。Chicken pox is a contagious disease．水痘是一种传染病。serious：严重的。Doctors said that his conditions were serious but stable．医生说他的情况严重但还稳定。worrying：令人担心的。His conditions are worrying to us．他的情况令我们担忧。