1
This sort of problems can be difficult to solve.
This sort of problem can be difficult to solve.
These sorts of problems can be difficult to solve.
Use this/that sort of + singular noun: ‘this sort of problem’, ‘that sort of behaviour’.
Use these/those sorts of + plural noun: ‘these sorts of problems’, ‘those sorts of activities’.
We use kind and type in the same way.
2
They sell all sort of things in that shop.
They sell all sorts of things in that shop.
I don’t enjoy those sort of films.
I don’t enjoy that sort of film.
I don’t enjoy those sorts of films.
After plural words such as all, these, those, many and several, use the plural forms sorts, kinds and types: ‘all sorts of things’, ‘many types of cars’.
3
A minibus is a sort of a small bus.
A minibus is a sort of small bus.
Use a sort of + adjective + noun to mean ‘a type of’: ‘This is a sort of traditional dance.’ Do not put another a/an after of.
The film was a sort of boring.
The film was sort of boring.
In informal English, sort of can mean ‘in a way’, ‘more or less’ or ‘not completely’. In this use, do not put a before sort of: ‘The film was sort of boring.’ ‘I sort of understand.’
See KIND OF