________of the people on the Net ________China's economy is among the strongest in the world.

A．Four fifth; believes

B．Four fifth; believe

C．Four fifths; believe

D．Four fifths; believes

会引起牙本质胶原蛋白变性的表面处理剂有（）。

A.EDTA或10-3溶液

B.枸橼酸、丙酮酸

C.5.3%草酸盐溶液

D.氨基酸

E.钙化液