A Japanese ship is moving to China. It’s carrying many gold coins（金幣） and jewels（珠寶）. Jack is the captain（船長）. He locked（鎖） the most expensive（貴的） diamond necklace（鉆石項(xiàng)鏈） in his cabin（船艙）. But someone stole（偷） it when he left（離開） the cabin. Four people were on duty（值班） at that time. They are the first mate（大副），two sailors（船員） and the cook. When the theft（偷竊） happened（發(fā)生），where were they？ Let’s listen to what they said. You may find who the thief（小偷） is.