读下面一段短文，用括号内所给单词的适当形式填空。
American summers are filled with outdoor picnics, baseball games and swimming pools. Summer in America is a time (76) _____ (enjoy) the outdoors, no matter how hot it might be. Let’s take a look at some of the popular drinks.
Lemonade is (77) ___ (common)of all American summer drinks. It (78) _____ (make)by mixing lemon juice, water and sugar. It is usually served very cold, with ice. Ice tea is another  popular summer drink in America. Ice tea is usually served in a tall glass of ice. Many Americans(79) ___ (choose) to add sugar to sweeten the drink. This drink is often drunk in the afternoon while relaxing in the shade. Ice tea is now also sold by the bottle , at almost any store in America.  
The Slurpee, a famous American drink in recent years, is a great way to cool off in the summer heat. It is a mix of ice, sugar and fruit juices. However, the drink is mostly made of ice. They can (80) ____ (buy) at most small convenient stores. Slurpees are popular with young Americans. Milkshakes have a long history in America . It is made of a mix of ice cream , milk and flavoring.