【问】 They looked in the folds of her dress，in the folds of her cloak，in the pockets，everywhere. It(=The necklace) was not to be found.(许国璋《英语》第四册，P. 60)不明白这里的be to具有什么样的词汇含义。我查阅了许多语法书，都说be to有两种含义。
 A.表示将来的一种安排：
 1. Their daughter is to be married soon. (CGEL)
 他们的女儿马上就要结婚了。
 2. The Prime Minister is to visit Canada next month. (PEU)
 首相定于下月访问加拿大。
 B.表示“应该”、“应当”、“必须”(可表示命令)：
 1. You are not to smoke in this room. (LDCE)
 你不可在这房间里抽烟。
 2. The form is to be filled in and returned within three weeks. (PEU)
 请于三周内将表填好并返回。
 【答】 be to+V这个结构能够表示许多意思。其中有一个意思是一般的语法书所没有谈及的，那就是：be to还可用于表示“可能”。例如：
 1. Such books are to be found in the library.
 这样的书在图书馆里就能找到。
 2. Not a sound was to be heard. (Mis)
 一点儿声音也听不到。
 3. Not a soul was to be seen. (Mansfield)
 看不到一个人影。
 4. She was nowhere to be found. (PEU)
 哪儿也找不到她。
 5. Many new beautiful buildings are to be seen in the streets of London. (CGEL)
 在伦敦街道上能看到许多新建的漂亮大楼。
 6. A complete contents is to be found in Volume Ⅰ.
 在第一卷可以查到全部目录。
 7. We looked and looked，but the ring was nowhere to be found.(LDCE)
 我们找了又找，这颗戒指再也找不到了。
 8. He was never to see his wife and family again. (ALD)
 他再也不可能见到他的妻子和其他家人了。