—_________ is your science teacher?
—My science teacher is at home.
A:When
B:Who
C:Where
D:What
探究烧杯内溶液中溶质的成分.
(1)如图,∠1、∠2是直线____ 、____ 被第三条直线____ 所截成的____ 角.
(2)在同一平面内,不重合的两条直线的位置关系只有____ 和____ 两种.
孝敬父母,最重要的是()