This is our office.
A:teacher's
B:teachers'
C:teacher'
①不通空气时,冷水中的白磷不燃烧;
②通空气时,冷水中的白磷不燃烧;
③不通空气时,热水中的白磷不燃烧;
④通空气时,热水中的白磷燃烧.
能证明可燃物必须达到一定温度(着火点)才能燃烧的实验事实是( )
— Whose ____ (knife) are in the desk? —They are Ann’s and Dick’s.
读如图回答下列问题.