B) Fill in the blanks with "Must - Mustn't - Have to - Has to" (×4= 16) 1- We ..... ................ cut down trees to prevent the environment. 2- People ..... ... ..... stop wasting water to prevent drought. 3- The exams are next week. I ...... .......... work harder. 4- She ...... ..... go shopping today. Shee needs alot of things.