A simple sentence is built from the minimum of a subject and a main verb. It can be very short in length (but doesn't have to be): 'The angry dog barks.' It puts across one simple idea ...
Simple sentences are important for making clear points. Be careful though - if you only ever use simple sentences in your writing you don’t add much detail, so your reader could lose interest.
The 54-year-old has not gone to jail because in Spain sentences of less than two years ... system have embarked on a campaign to slash basic rights of freedom of speech - and that musicians ...