第21题: [单项选择]When he was a student, his father gave him a monthly ________ to cover his expenses. A. currency B. allowance C. pay D. permission 参考答案:B 答案解析:[解析] 四个选项中有三个与钱有关。B.allowance零花钱,津贴;A.currency货币;C. pay报酬;D. permission允许。根据句意应选B。句意为:他是学生时,他父亲按月给他一