When something lengthens or when you lengthen it, it increases in length. 使变长; 变长
verb [vt. 及物动词] 使延长；加长
The evening shadows were lengthening. 傍晚的影子正在变长。
verb [vi. 不及物动词] 延长；变长
Vacations have lengthened and the work week has shortened. 假期延长了，工作周变短了。
