а) If a machine breaks down, you have to repair it.
b) An industry which is disappearing in said to be declining.
c) If you create a company, you start or set one up.
d) When sales are falling, we say your market share is dwindling.
e) We (sorry no ideea) a plan or system when the situation changes.
f) A difficult situation can be called a collapse.
g) A company needs to recruit good staff if it wants to succeed