Although he didn't know the answer, he still raised his hand. The test began when all the students arrived. Be written to communicate, not merely to impress. At the present time there is . . . . Iyer states that the purpose of punctuation marks is to guide readers through written text.
Punctuation marks help to facilitate communication between the writer and reader.
A comma indicates where a pause should be. A period indicates a concluding thought. Contain only specific, concrete language rather than general, abstract language. The car gets good gas mileage. The Geo gets about 50 mpg on the highway and 45 mpg in the city.