A:杂交与自交
B:正交与反交
C:自交与测交
D:杂交与测交
体积和质量都相等的铁球、铜球、铅球,则下列说法正确的是( )
下列各组离子在溶液中一定能大量共存的是 ( )
After school, he____ volleyball____ his friends.