A:concerned about
B:concerned with
C:concerned for
D:concerned i
做“绿叶在光下制造淀粉”的实验时,要先将天竺葵放到暗处一昼夜,其目的是( )
函数y=ax-2+loga(x-1)+1(a>0,a≠1)的图象必经过定点 ( )