TASK DEFINITION: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
PROBLEM: An artesian aquifer is trapped between rocks or clay which causes the pressure .

SOLUTION: An artesian aquifer is trapped water , surrounded by layers of impermeable rock or clay which apply positive pressure to the water contained within the aquifer .

PROBLEM: Littlehampton is a seaside town in Arun , West Sussex , England .

SOLUTION: Littlehampton is a town , seaside resort and pleasure harbour , and the most populous civil parish in the Arun District of West Sussex , England .

PROBLEM: France has a multi-party system , which means that several political parties must form coalitions in order to form a government .

SOLUTION:
France has a multi-party political system : one in which the number of competing political parties is sufficiently large as to make it almost inevitable that in order to participate in the exercise of power any single party must be prepared to negotiate with one or more others with a view to forming electoral alliances and / or coalition agreements .