There are on the desk.[ ]
A.any pens
B.two pens and a ruler
C.a ruler and two pens
答案:B
恒牙列期下颌角为()
A.100°~120°
B.120°~125°
C.130°~140°
D.140°~160°
E.150°~170°
含有Fe3+的化合物是()
A.血红蛋白
B.亚铁血红蛋白
C.肌红蛋白
D.碳氧血红蛋白
E.高铁血红蛋白