近交系动物
参考答案：
是指至少经过20以上连续全同胞或亲子交配，品系内所有个体都可追溯到其源于第20代或以后代鼠的一对共同祖先的动物群。
—Would you mind ____ the room?
—OK. I’ll do it right away.
A．clean
B．cleaning
C．cleaned
D．to clean
We have ______ good things to eat.[ ]
A. so much
B. too much
C. much too
D. so many
