A. and B. but C. or D. than
A. against B. for C. of D. through
A. pursued B. involved C. bargained D. avoided
A. 摄入氮 B. 吸收氮 C. 储留氮 D. 粪代谢氮 E. 尿内源氮
A. in B. at C. over D. from
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