内因子缺乏将导致
A．再生障碍性贫血B．缺铁性贫血C．恶性贫血D．巨幼红细胞性贫血E．臼型地中海贫血
参考答案：D
We have classes _____ Monday _____ Friday.[ ]
A. at, to
B. from, to
C. from, for
D. on, on
I found _________difficult to work out the problem.
A it’s B this C that D it
