1. While two detectives were keeping guard at the door， two others opened the parcel.
当两位侦探守住门口时，另外的两位侦探打开了包裹。
知识点1 keep guard at the door 把门，守门
知识点2 关于“在……旁”的表达：
（1）near 在附近（可近可远）
（2）by 在……边
（3）next to 紧挨着，紧紧相连
（4）at 在……旁（常接门、窗、桌子）
（5）beside 在……旁边
2. To their surprise， the precious parcel was full of stones and sand!
让他们吃惊的是，这个所谓的贵重的包裹里面被塞满了石头和沙子！
知识点1 to one's surprise 让某人吃惊的是
To his surprise, I gave him two glasses of beer immediately. 让他感到意外的是，我马上给了他两杯啤酒。
类似结构的表达有：to one's amusement 让某人感到好笑的是
to one's disgust 令人反感的是
知识点2 be full of sth. 充满某物
The small ship is full of water. 这条小船里全是水。
