施必牢螺母M24、M27、9级螺栓、10.9级。
参考答案:错
-Did your parents learn English?
-____________.They spoke well. [ ]
A. Yes,he did
B.No,they don't
C.Yes,they did
写出下列物质或微粒的电子式(每空1分)
(1) CaCl2 (2)CO2 (3) KOH
(4) HF (5) Na2O2 (6) N2
(7) 镁离子 (8)硫离子 (9)NH4Cl_________ (10) Cl2____________________