白化病是由隐性致病基因（a）控制的．一对肤色正常的夫妇生下一个白化病的孩子，这对夫妇的基因组成都是____，如果他们再生一个孩子，患白化病的可能性为____%．
— Why did she ______ your invitation?
— Because she had an important meeting to attend that day.
下列各种原子各1g，所含原子数最多的是（ ）
