Sentence 4: His well drained roads were built with three layers: large stones; excavated road material; and a layer of gravel.
Which of the following changes should be made to CORRECT sentence 4?

In order to correct sentence 4, you should insert a hyphen after \u201Cwell.\u201D It is grammatically appropriate to connect two words to form a new word that begins with a prefix or to serve as a single adjective. Therefore, \u201Cwell drained\u201D should be rewritten as \u201Cwell-drained.\u201D The sentence is written in the past tense; therefore, \u201Cwere\u201D is the correct word to use, as \u201Care\u201D is in the present tense. It is appropriate to use a colon to introduce a list and \u201CHis\u201D is used correctly.