下列现象中,不是生物对环境适应的是( )
A:北极熊白色的体毛
B:鱼的体型为梭型
C:牦牛的绒很保暖
D:孔雀开屏
则:
用图甲所示的装置测出凸透镜的焦距,并“探究凸透镜成像规律”,当蜡烛、透镜、光屏位置如图乙时,在光屏上可成清晰的像.下列说法正确的是( )
Jim tried hard,and finally he ______ his dream of being the best football player in his school.