动物体内嘧啶代谢的终产物不包括（）。
A.NH3
B.C02
C.尿酸
D.β-丙氨酸
E.β-氨基异丁酸
参考答案：C
Mary is a humorous and warmhearted woman and that is ________ she is a most popular person in her community.
A．whether
B．because
C．how
D．why
2.37是由2个______，3个______，7个______组成的．
