刘某与曹某签订房屋租赁合同，后刘某向法院起诉，要求曹某依约支付租金。曹某向法院提出的下列哪一主张可能构成反诉（）

A.刘某的支付租金请求权已经超过诉讼时效 

B.租赁合同无效 

C.自己无支付能力 

D.自己已经支付了租金

172. Since the disaster of September 11, American economy has got into a jam. The underlined part probably means _____.

A．had a lot of trouble

B．become very good

C．got into a stop

D．developed rapidly