Replace 'have' with 'has'.
Here, the subject 'land' is an uncountable noun i.e. used in singular sense, so the verb should also be singular.
been ploughed.
Half of, One third of, Two thirds of, Three-fourths of
Some, Some of, All, All of, Enough, Most, Most of, Lots of, A lot of, Plenty of |
- If noun is uncountable, it is used in 'singular' sense, then verb is also 'singular'.
e.g.
needed.
available.
- If noun is countable, it is used in 'plural' sense, then verb is also 'plural'.
e.g.
closed today.
mortal.
there.
