must与should表示建议和禁止 — 英语填空题

根据句意，用 must, mustn't 或 should 填空（每词限用一次）。1. The doctor says, 'You are too heavy. You ___ eat more vegetables and do exercise.' 2. The sign on the wall says 'No swimming'. So we ___ swim in this lake. 3. It's late. You ___ go to bed now, or you will be late for school tomorrow.