She thought it was worthwhile for her to teach in the small village to make a ______ to the life of the children there.
A:difference
B:sense
C:study
D:discovery
香豌豆的花色有紫花和白花两种,显性基因C和P同时存在时开紫花。两个纯合白花品种杂交,F1开紫花;F1自交,F2的性状分离比为紫花:白花=9:7。下列分析不正确的是()