循环中的FGF-23主要来源于哪种组织（）
A.骨组织
B.肾脏
C.小肠
D.肝脏
参考答案：A
He seems __________ what he is looking for. [ ]
A. to have forgotten
B. to forget
C. forgetting
D. being forgotten
睾丸的位置异常不仅影响_________，而且易发生_________。
