You don't have to go out to buy__hamburger,since the fast-food restaurantdedelivers free of__charge A a,a B the;the C不填；不填 D a;不填

You don't have to go out to buy__hamburger,since the fast-food restaurant
dedelivers free of__charge A a,a B the;the C不填；不填 D a;不填

d,hamburger是可数名词,前面要加冠词,但它不是特指所以用a,而free of charge是固定搭配