You should when you are giving an oral presentation. a. hide your purpose b. use a humorous tone c. avoid drawing clear conclusions d. make eye contact with the audience

D. make eye contact with the audience

Answer(true);

Polyethylene is a strong synthetic polymer that can be used to make toys and bottles. this makes plastics which are important also to people but sometimes it lead to harmful environmental effects such as global warming if these plastics are burned.