第21题: [单项选择]If some one need help ______ meet a trouble ______ seems not to be got over easily, the other must not leave until overcome it. A. Who; which B. Whom; with which C. When; which D. When; with which 参考答案:C 答案解析:本题考查的知识点是从属连词与关系代词。 句意:如果一个人遇到了似乎是不可逾越的障碍,需要帮助时,另一位一定在克服后才离开。