YOU SAID:

the ground is wet with rain that must have fallen overnight

INTO JAPANESE

一晩で降ったに違いない雨で地面が濡れている

BACK INTO ENGLISH

The ground is wet with the rain that must have fallen overnight

INTO JAPANESE

一晩で降ったはずの雨で地面が濡れている

BACK INTO ENGLISH

The ground is wet with the rain that should have fallen overnight

INTO JAPANESE

一晩降ったはずの雨で地面が濡れている

BACK INTO ENGLISH

The ground is wet with the rain that should have fallen overnight