—________ great fun we had at the party last night!
—Yes, it was so exciting that everyone was happy.
A:How a
B:How
C:What
D:What a
曲线y=-4-x2x≤0的长度为( )
在下列生理活动中,细胞内基因的分子结构最可能发生变化的是( )
某工人用如右图所示的装置把重240N的物体提高1m,所用的拉力为150N,则该滑轮组的机械效率是____ ;若不计摩擦,则动滑轮的重为____ N.