胆红素主要是体内哪种物质分解代谢的产物（）
A.血红素
B.核苷酸
C.铜蓝蛋白
D.胆固醇
E.脂肪酸
参考答案：A
Is this the reason _____ at the meeting for his carelessness in his work? [ ]
A. he explained
B. what he explained
C. how he explained
D. why he explained
通过提供客观证据对规定要求已得到满足的认定称之为（）
A.监视
B.检验
C.验证
D.证实
