Look! What a nice and clean toilet! Yes. It ______ every morning.
A:is cleaned
B:has been cleaned
C:is being cleaned
D:was cleaned
消化道中,消化蛋白质和淀粉的起始部位分别是
—Ten.
如图,一次函数y=kx+b与反比例函数y=6x(x>0)的图象交于A(m,6),B(3,n)两点.