To lengthen something is to make it longer, or to become longer yourself.

something某樣東西 lengthen弄長 is就是 to make it longer讓它變得更長 or或是 to become longer yourself自己變得更長

A tailor can lengthen trousers. A meeting lengthens when people keep talking. Days lengthen after winter.

A tailor裁縫 can lengthen trousers可以把褲子弄長。when people keep talking人一直講話時 A meeting lengthens會議就會拖長。after winter冬天過後 Days lengthen白天會變長。

Both “make longer” and “become longer” are normal.

Both "make longer" and "become longer"「make longer」和「become longer」這兩種說法 are都 normal正常。

Though actually, we do not lengthen everything that grows: a child grows, we do not “lengthen” a child.

Though actually不過其實, we do not lengthen everything that grows我們不會把所有會長大的東西都弄長: a child grows小孩會長大, we do not "lengthen" a child但我們不會說要「lengthen」一個小孩。

For time, lengthen is fairly calm; if the wait feels painful, people say it dragged on. Extend often means add time to a deadline or add space; lengthen stays closer to length — how long a thing is, in space or in time.

For time在講時間的時候, lengthen is fairly calmlengthen語氣算平和; if the wait feels painful如果等待讓人覺得難熬, people say it dragged on大家會說它拖拖拉拉的。Extend often meansExtend常常是指 add time to a deadline把截止時間往後延 or add space或是把空間加大; lengthen stays closer to lengthlengthen則比較貼近length本身── how long a thing is不管一樣東西有多長 in space or in time不管是空間上還是時間上。

You will hear it with clothes, shadows, days, and speeches.

You will hear it你會聽到這個字用 with clothes在衣服, shadows影子, days白天, and speeches還有演講上。