描述测量过程的方法 — 英语情景题

Read and complete the dialogue. Sam: Lily, how do we measure one minute? Lily: We can use an egg timer. Sam: What do we do first? Lily: (1)________, turn the egg timer over. Sam: What do we do then? Lily: Wait until all the sand falls down. Sam: How do we know it is one minute? Lily: When the sand stops, one minute is (2)________.