当正方体的棱长之和是72厘米时，它的表面积与体积相等。
如图，⊙O的直径AB与弦CD的延长线交于点E，若DE=OB，∠AOC=74°，则∠E=____ ．
防止金属锈蚀是保护金属资源的有效途径，锌铬黄（化学式为ZnCrO4）常用于制防锈涂料．锌铬黄中铬元素的化合价为（ ）
My brother usually _____ in a townhouse with us. But now he _____ for an apartment near the school.
