In this sentence: 石猴看了看四周”的句子, what is the grammar behind the 看了看 construct? I know it means "had a look", but the grammar v+了+v is one I had never seen before.
看了看 - a "brief" look/eying briefly. Note, without 了, 看看 means "see how ..., such as "讓我們換個方法看看 - Let's try the other way see how it goes, and "讓我看看你有多聰明" - Let me see how smart are you".
There are not too many phrases in this pattern, all can be explained as a "brief" act:
笑了笑 (a brief smile), 停了停 (stop briefly), 望了望 (looking briefly), 叫了叫 (barking briefly), 走了走 (walking briefly), 跑了跑 (running briefly), 動了動 (a brief/slight movement), 撇了撇嘴 (表示不㞕/不信服/不同意/不相信), a brief slanting up or down the corner of the mouth to signal unconvincing/disagree/disbelieve ), 張了張嘴/口 (open the mouth briefly and close immediately signals wanting to say something but couldn't say it) 張了張眼 (open the eye briefly), 貶了眨眼 (a swift close and open an eye to signal something), 聽了聽 (listen briefly - usually performed by a doctor or nurse during physical exams to check the patient's heartbeat, wrist pulses...etc), 想了想 (thinking briefly).
Reduplication of a verb indicates it happens 'slightly' or 'briefly'
看 = look
看看 = slightly look/ briefly look
想 = think
想想 = slightly think/ briefly think
笑 = laugh
笑笑 = slightly laugh/ briefly laugh
了 is a verb particle that indicates a verb is completed.
When 了 is used with a single verb, it is placed after that verb.
看了 = have looked
想了 = have thought
笑了 = have laughed
However, when 了 is used with a verb reduplication, it is inserted between the two reduplicated verbs
看了看 = slightly looked/ briefly looked
想了想 = slightly thought/ briefly thought
笑了笑 = slightly laughed/ briefly laughed