句子解釋：
let 英[let] 美[l?t]
[詞典] 允許，任由; 讓，隨; 假設; 出租;
[例句]People said we were interfering with nature, and that we should just let the animals die
人們說我們是在幹涉自然界，還說我們應該任由動物死去。
heartbeat 英[?hɑ:tbi:t] 美[?hɑ:rtbi:t]
n. 心動，心跳，心搏; 中心; 感情; 重要特征;
[例句]Your baby's heartbeat will be monitored continuously.
寶寶的心搏將會受到持續監控。