It was with great joy _______ he received the news ____ his lost son would soon return home.
A:because; that
B:that; that
C:because; which
D:that; \
如图,△OAB以O为位似中心放大1倍到△A′OB′,写出变化前后各顶点的坐标,并指出坐标的变化规律.
(2015•阜阳)增加室内换气次数是减轻居室环境污染的关键性措施.
羊的毛色白色是显性(用B表示),黑色是隐性(用b表示).一只白色公羊与一只黑色母羊交配,生下的小羊全部是白羊.请问公羊的基因组成是____,母羊的基因组成是____.