You should have told me so before.
你早該告訴我的。
Honestly, you might have told me!
說實話，你事先應該告訴我呀！
Somebody should have told me.
應該有人告訴我才是。
'You should have told me!' she flared at him.
“你應該告訴我的！”她氣沖沖地對他說。
You should have told us. But it's just like you not to share
你應該早告訴我們的。不過你就是這么個人，把事情都藏在心里。