at the drop of a hat 和 back s.b up

at the drop of a hat 和 back s.b up at the drop of a hat 的意思 he'll play tennis at the drop of a hat.翻译 he'll play tennis at the drop of a hat.翻译（口语） "at the drop of a at the back of 和at back of的区别 above the ground和a drop of He will kill at the drop of a feather? you can feel a little drop of water on the back of you hand. A tall （ ）is at the back of the school.It's our school libra what's the name of girl ()a red hat on at the back of; in the front of; try to; arrive at ; get up;