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
I _______ it, but I _______ nothing. [ ]
A. hear; listen to
B. listen to; hear
C. listen to; hear to
D. hear to; listen
Lewin was interested in taking research beyond books and looking at how it could ____ real social change
A．bring up
B．bring about
C．bring in
D．bring out
