A:x+y<z
B:平衡向右移动
C:B的转化率升高
D:C的体积分数降低
— How foolish I was!
— ________ you have realized that, stop blaming yourself.
已知等差数列{an}的公差为2,若a1,a3,a4成等比数列, 则a2=( )