A：∀x∈R,x2<0
B：∀x∈R,x2≤0
C：∃x∈R,x2≥0
D：∃x∈R,x2<0
已知9am+nbn+1与﹣2a2m﹣1b2m﹣1的积与5a6b6是同类项，求m，n的值．
Trees and flowers _______ every year to make our school more beautiful.
填一填。
名山____ 绵延____
蛋白质消化的最终产物是（ ）
