A:光球层和色球层
B:色球层和日冕层
C:光球层和日冕层
D:日珥和太阳风
Tell your friend not to take the pills _______ he may have health problems in the future, _______ it is too late.
已知命题P:∃x∈-∞,0,2x<3x,命题q:∀x∈0,π2,tanx>sinx,则下列命题为真命题的是( )