[see also: that
For which f does equality hold in this inequality?
Where there is a choice of several acceptable forms, that form is selected which......
Let I be the family of all subalgebras which contain F. [Or: that contain F; you can use either that or which in defining clauses.]
We denote the complement of A by Ac whenever it is clear from the context with respect to which larger set the complement is taken.
The map f, which we know to be bounded, is also right-continuous. [Not: “that we know''; do not use “that'' in non-defining clauses.]
Hence F is compact, which yields M=N. [Not: “what yields'']
......, which completes the proof.
[Note the difference between what and which in sentences similar to the last two examples: what refers to what follows it, while which refers to what precedes it.]