We have encountered this question when we try to read Heim and Kratzer's book. This following picture is taken from Heim & Kratzer (1998: 40).
Our answers are simply based on the subscripts:
(a) <<e,t>, <e,t>> (b) <<e,<e,t>>, <e,t>> (c) <e,<<e,t>, <e, t>>> (d) <<e,t>,t> (e) invalid? (f) <<e,t>,<<e,t>,t>>
However, we could hardly translate those λ-calculus into natural language. Were formal semantics in general meant to be used for syntax-to-semantics mapping but not the other way around? See more comments in this blog.
Any clarification or comments are welcome!