A:I was neither
B:neither was I
C: I was either
D:either was I
5×6=____ 8×5=____ 25÷5=____
24÷6=____ 27÷3=____ 18÷9=____
18÷3=____ 3×7=____ 32÷4=____
已知烟煤的热值是2.9×107J/kg,那么( )
如图所示,一人沿一直山坡,自坡底A以速率v1跑到坡顶B,随即又以速率v2返回到A,已知AB间的距离为s,那么人在这一往返过程中的平均速度为( )