消化腺分为两类:一类是位于消化道内的消化腺,另一类是位于消化道外的消化腺.下列属于后者的是( )
①肠腺 ②胰腺 ③胃腺 ④肝脏.
A:①③
B:②④
C:②③
D:③④
尺规作图作∠AOB的平分线方法如下:以O为圆心,任意长为半径画弧交OA、OB于C、D,再分别以点C、D为圆心,以大于12CD长为半径画弧,两弧交于点P,作射线OP,由作法得△OCP≌△ODP的根据是( )
—Jenny and Joe have________recently.
—How come?As far as I know,they have been good friends for many years.