单项选择题
A.N2和CO2 B.Cl2和CO C.CO2和NH3 D.H2S和CCl4
A.AB+AC+BC B.A+B+C C. D.
A.y=Acosπ[t-(x-5)/6] B.y=Acosπ[t-(x+5)/6] C.y=Acosπ[2+(x+5)/6] D.y=Acosπ[t+(x-5)/6]