—Do you want to keep goldfish?
—No, they are ______ difficult for me______ take care of.
A:so; that
B:not; enough to
C:too; to
D:such; that
系谱图是用于记载家庭中某些成员具有某个性状的树状图表.如图为某单基因遗传病的系谱图.请据图回答(显隐性分别用A、a表示):