通过再贴现和( )两种途径，商业银行可以向中央银行借款。
A．再贷款
B．购买央行票据
C．外汇抵押贷款
D．发行商业银行票据
参考答案：A
—Last week American doctors ______ his foot.
—They say Liu Xiang may run ______ after the operation. [ ]
A. operated on; even faster
B. operation on; even fast
C. operated to; much faster
D. operated; more faster
请用不超过150字的篇幅，概括出给定资料所反映的主要问题。要求：全面，有条理，有层次。
