Schools across China are expected to hire 50000 college graduates this year as short-term

teachers , ________ reduce unemployment pressures. [ ]

A. help          

B. to have helped        

C. to help        

D. having helped

停止流通的人民币和残缺、污损的人民币，按照中国人民银行的规定兑换，并由中国人民银行负责回收、销毁。