A:云贵高原
B:内蒙古高原
C:黄土高原
D:青藏高原
用三段论证明:通项为an=pn+q(p,q为常数)的数列{an}是等差数列.
—I want to buy the book Harry Potter. Do you know its ________?
—Not quite sure. Maybe 30 yuan.
当家庭遇到类似右图所示情况时,正确的认识是( )