We can use sentences for four main purposes in communication:
 To make a statement:
That car is travelling very fast.
 To ask a question:
Is that car breaking the speed limit?
 To give an order or make a request:
Don’t drive so fast!
 To make an exclamation:
How fast that car is travelling!
Each has a different structure, but since statement sentences are by far the commonest, the explanations in this introduction concentrate on them.
For Scientific english editing and Medical Writing Services visitwww.manuscriptedit.com