——————It's 8 o'clock()
A.How many books do you have
B.What time is it
C.How old is it
WHATTIMEISIT?
A.How many books do you have
B.What time is it
C.How old is it
WHATTIMEISIT?
A.t=2 s时刻,振子的位置在O点左侧4 cm处
B.t=3 s时刻,振子的速度方向向左
C.t=4 s时刻,振子的加速度方向向右且为最大值
D.振子的周期为8 s
A.SiO2eq \o(――→,\s\up7(NaOHaq),\s\do5(△))Na2SiO3eq \o(――→,\s\up7(CO2),\s\do5())H2SiO3
B.Seq \o(――→,\s\up7(O2),\s\do5(点燃))SO2eq \o(――→,\s\up7(BaCl2aq),\s\do5())BaSO3
C.NH3eq \o(――→,\s\up7(O2),\s\do5(催化剂/△))NO2eq \o(――→,\s\up7(H2O),\s\do5())HNO3
D.MgCl2·6H2Oeq \o(――→,\s\up7(△),\s\do5())MgCl2eq \o(――→,\s\up7(电解),\s\do5())Mg