A:in where
B:to the east of which
C:to the east of it
D:in the east of that
下列各项中,没有语病的一项是( )
673×33+673×67
=673×( ____ +____ )
=673×____
=____
(Ⅰ)求证:CM⊥平面ADM;
(Ⅱ)若P是棱AB上的动点,当 APAB 为何值时,二面角P﹣MC﹣B的大小为60°.