I make $2,000 a week, 60 surely won't make ______ difference to me. [    ]

A. that a big            

B. a that big          

C. big a that      

D. that big a

有一个两位数，十位数字为a，个位数字为b，若将十位数字和个位数字调换，那么新的两位数可表示为[ ]

A．ba

B．10b+b

C．10b+a

D．10a+b