动作动词祈使句 — 英语阅读题

Read the passage and answer the question. It is English class. Miss Li says, "Stand up, please!" The pupils stand up. Then Miss Li says, "Sit down, please." The pupils sit down. Miss Li opens the book and says, "Open your books." The pupils open their books. She says, "Close your books." They close their books. Then Miss Li says, "Look at the blackboard, please." The pupils look at the blackboard. Question: What does Miss Li say first at the beginning of the class?（上课一开始，李老师先说了什么指令？）