-- Would you please show me your new radio?
-- I'm sorry. I ____ (listen) to the music. I didn't catch you.
1 23 ×____=1 47 ÷1____=____: 78 =1.
下列说法有误的一项是( )
已知An5=nAn3,求n.
人类生命的起点是受精卵,受精卵在人体内的形成场所和胎儿发育的场所依次是( )