A:2450
B:2550
C:2500
D:2652
—I will have an important test tomorrow. I feel stressed now.—__________ and believe youself. You will pass it.
图是人工种子的结构简图,对其叙述不正确的是( )
公民的权利,需要来自家庭、学校、社会及法律的保障,最重要、最有效的是( )