等边三角形、平行四边形、矩形、圆四个图形中，既是轴对称图形又是中心对称图形的是（ ）
圆、矩形
That George will marry Alice, ______ has not been announced yet, has spread around.
A．that
B．which
C．what
D．who
物理吸附法不会明显改变酶分子的高级结构。
