SummarizationRead each of the following short paragraphs and complete the phrase or sentence that expresses the main idea of the paragraph. The first letter of the missing word is given before the blank.Paragraph 3.All plants and animals that have been studied carefully (including humans) seem to have build-in clocks. They know the time naturally and correctly without any help from outside.3.To have a b_______ clock.
【正确答案】：biological
【题目解析】：P181
