家鸽骨骼的特点是（）
A、厚而坚硬
B、薄而轻，长骨中空
C、长骨较厚，骨髓发达
D、厚且多愈合
参考答案：B
已知f（x）为一次函数，若f[f（x）]=4x+8，求f（x）的解析式．
This is an unpleasant subject_ ____ we might argue for a long while. [ ]
A. in which
B with them
C. about which
D with it
