半解剖式人工牙的牙尖斜度为()
A.0°
B.10°
C.20°
D.30°
E.40°
参考答案:C
— Would you like something to drink?
— I’m not thirsty.
A.No, thanks.
B.Yes, please.
C.OK.
D.Some water, please.
(每空2分,共6分).12.4g Na2R 含有Na+0.4mol,则Na2R的摩尔质量为 ,R的相对原子质量为 ,含R1.6g 的Na2R的物质的量为