Question

because I was scared I'd get in trouble for playing somewhere I shouldn't have been. 为什么

because I was scared I'd get in trouble for playing somewhere I shouldn't have been. 为什么是用have been呢

Answer 1

because I was scared I'd get in trouble for playing somewhere I shouldn't have been.
因为我害怕我会在某处玩的麻烦。我不应该。
语法点是trouble作为可数名词使用，意为“麻烦，困难”

have trouble (in) doing ,
have trouble with +n.
trouble是可数名词,变复数加s
相关短语:
a sea of troubles 困难重重
ask for trouble [口]自讨苦吃
be a trouble to 对...是一个麻烦(或讨厌的人)
be in troubles with 和...闹纠纷
bear sb.'strouble on one's back 替某人担当责任
borrow trouble 自寻苦恼; 杞人忧天
don't trouble 别费事
get into trouble 招致不幸,陷入困境,遭受处罚 (使)未嫁怀孕 被捕,坐牢
get out of trouble (使)摆脱不幸[困境]; (使)免受责骂[处罚]
give sb.trouble 麻烦人家
go to the trouble 不怕麻烦; 特意(后常接 of + 动名词)
have trouble with 有...病痛
I'll trouble you to 劳驾你...,请你...
make trouble 闹事,捣乱
make trouble for 给 ...带来麻烦
meet trouble halfway 自寻烦恼
no trouble (at all) [口]这不费事,容易得很,没什么
put oneself to (the) trouble 不怕麻烦,愿意费力
save oneself the trouble (of) 省掉(...的)麻烦
take (the) trouble 尽力设法; 不怕费事
teething trouble 出牙期的病痛; [喻]事情开始时的暂时困难
trouble sb.for sth.[口]麻烦某人做某事(如递某物、告诉时间、比赛分数等,常用于疑问句)

Answer 2

shouldn't have done表示本不该做的事却做了
--------------Shanghai Onesmart Education is glad to serve for you.