— They're books.
A:Are these English books?
B:Are those English books?
C:How do you spell it?
D:What're these in English?
对以下两幅世界名画的表述错误的是( )
已知数a满足2004-a+a-2005=a,求a﹣20042的值.
下面列举的四个光现象中,属于光的反射现象的是( )
苹果从树上落向地面而不飞上天空,是因为( )