A:−16+2k,56+2k,k∈Z
B:−56+2k,16+2k,k∈Z.
C:−56+2kπ,16+2kπ,k∈Z
D:16+2k,76+2k,k∈Z
同温同压下,质量忽略不计的两气球A和B,分别充入X气体和Y气体,且充气后两气球的体积相同.若相同条件下,A气球放在CO中静止不动,B气球放在O2中上浮.下列叙述或表示正确的是 ( )
如图,AB为⊙O直径,CD为⊙O 的弦,∠ACD=28°,则∠BAD的度数为____°.
如图为一个几何体的侧视图和俯视图,若该几何体的体积为43,则它的正视图为( )
-Your paintings are so great, David! When did you learn to paint?
-Three years ___________.