【单选题】Both Bill and Mary produce t-shirts and hats. If Bill’s opportunity cost of 1 t-shirt is 4 hats and Mary’s opportunity cost of 1 t-shirt is 3 hats, then
A.
Bill has a comparative advantage in the production of t-shirts.
B.
Mary has a comparative advantage in the production of t-shirts.
C.
Mary has a comparative advantage in the production of hats.
D.
Bill has a comparative advantage in the production of both t-shirts and hats.
【单选题】已知函数f(x)=x 3 -3ax 2 +2bx在点x=1处有极小值-1,则a,b的值分别为( )
【判断题】八输入端的编码器按二进制数编码时,输出端的个数是3个。
【单选题】已知函数 在点 处有二阶导数,且 ,则下列结论正确的是( )
【单选题】已知f(x)=ax 3 -x 2 -x-1在x 0 =1处有极小值,则a的值为( )
【单选题】已知 在 处有极小值,则a 的值为( ).