sentence2_structure: a substance<>has<>a ph value greater than 7
sentence1: In this activity you will extract one to these natural acid-base indicators and use it to find the approximate pH values of some substances you might find at home or at school.
sentence2: If a substance has a ph value greater than 7,that indicates that it is base.
question: If a substance has a ph value greater than 7, what does it indicate?