计算（m+3n）2﹣（3m+n）2的结果是[ ]
A．8（m﹣n）2
B．8（m+n）2
C．8n2+8m2
D．8n2﹣8m2
答案：D
—Is this _____ Chinese dictionary?
—Yes, _____. [ ]
A. your; it is
B. you; it is
C. his; it's
D. her; it isn't
同源顺序(homologous sequences)
