Question

I waited until Tom and Jack arrived.Then _ began

为什么不选all of them
I waited until Tom and Jack arrived.Then _ began to do the experiment。
A all of them B the three of us C three of us D both of us
为什么不能选A 。all of them 与 B the three of us 有什么区别。

Answer 1

I waited until Tom and Jack arrived.Then _ began to do the experiment。
A all of them  B the three of us  C three of us  D both of us
不能选A 的理由是，从上下文看，除“我”、Tom 和Jack外无其他人，“ all of them"中的all指人时一般指三人或其上，如all为both则可选，当然意思也小有区别，就不是B说的”我们三个人做实验“，而成了”他们两个人做实验“了，“我”的角色可能是实验指导者了。

all of them是”他们（一般指三人以上，不包括自己）都“，  B the three of us 是”我们（包括自己）三人“。希望有帮助并采纳。

Answer 2

正确选项C three of us

I waited until Tom and Jack arrived.Then three of us
began to do the experiment.我一直等到汤姆和杰克到来，然后我们三位才开始做实验。

首先all of them不包括主语 I，如果是 I waited until Tom and Jack arrived.Then all of them

began to do the experiment.我一直等到汤姆和杰克到来，然后他们所有的人才开始做实验。
显然不合逻辑。
再有 B the three of us是个错误的干扰项

望楼主采纳

Answer 3

I waited until Tom and Jack arrived.Then _ began to do the experiment。
A all of them B the three of us C three of us D both of us
主语是第一人称，必须使用the three of us ，指我们三人，all of them他们所有人。

Answer 4

答案是B。the three of us 我们三人。其中us与the three是同位关系，等于we three.
选项A。不包括本人，不符合题意，故错。选项C，three of us我们中的三人，是部分与整体的关系，不符合题意，故错。

Answer 5

因为them 是宾格，只能作宾语，空格处需要主语，A不合适。
只能选B。
请采纳，谢谢。