Interested in Language
I ate sandwich in the restaurant yesterday.
s1. It was I that[who] ate sandwich in the restaurant yesterday.
s2. It was sandwich that[which] I ate in the restaurant yesterday.
s3. It was in the restaurant that[where] I ate sandwich yesterday.
s4. It was yesterday that[when] I ate sandwich in the restaurant.
Can each 'that' from s1 to s4 be changed into a relative form(who, which, where, when)?
I have hardly seen the case of s2 and s3.
And I can't find any accurate description about that.
Please let me know.
Thank you in advance.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.