lengthen: vt.延长，伸长，拉长。 lengthen a vowel 【语音】拖长母音音长。vi.变长；延伸；转为 (into). Summer lengthens (out) into autumn. 夏去秋来。 The days are lengthening. 白天长起来了。 The shadows lengthen. 天色渐黑；年纪渐老；死期已近。 lengthen out
In most people , the circadian cycle tends to be slightly longer than 24 hours . hence , most people have fewer problems with westward travel lengthening day than eastward travel shortening day 大部份人的生物钟均较24小时略长，因此朝西飞日子延长的旅客大多较朝东飞日子缩短的乘客少出现飞行时差反应症状。
