imperfectadj.不完美的;有缺点的;未完善的
imperativeadj.紧要的;必要的;祈使的n.紧要的事;命令;义务;驱使
imperceptiblenessn.看不见(难以察觉;觉察不到)
imperceptible given未感知到的材料
imperceptible change细微的变化
imperceptible teaching method潜移默化教学法
imperceptibleshades of meaning微妙的含义
imperceptible changes in temperature难以觉察的气温变化
"an imperceptible drop in temperature"
"an imperceptible nod"
"color is unperceivable to the touch"