A:肱三头肌收缩,肱二头肌舒张,肘关节弯曲
B:肱二头肌收缩,肱三头肌舒张,肘关节弯曲
C:肱二头肌收缩,肱三头 肌舒张,肘关节伸直
D:肱三头肌收缩,肱二头肌舒张,肘关节伸直
“This is a useful dictionary, I think. " "So it is, and it's __________ unusual one.”
18-6=____
19-6=____
15+4=____
14-4=____
5+13=____
16-3=____
18-4=____
5+7=____
4+8=____
15-5____
2+9=____
4+9=____
(Ⅱ)一段长为36m的篱笆围成一个矩形菜园,问这个矩形的长、宽各为多少时,菜园的面积最大.最大面积是多少?
对图中DNA分子片段的叙述,不正确的是( )
That is not____kite. That kite is very small,but____is very big. (I)