下列运算正确的是( )
A:a2·a3=a6
B:-a23=-a6
C:ab2=ab2
D:a6÷a3=a2
人体消化食物和吸收营养物质的主要器官是( )
单词拼写。
— Yes. He used to ________ the guitar, but now he is more _______ in playing soccer.