一直很困惑，怎么样算指代不清？有没有简单的判断标准？

比如说

（1）     GWD-10-Q39:

In Japan, a government advisory committee called for the breakup of Nippon Telephone and Telegraph Company, the largest telephone company in the world, so it would be two local phone companies and one long-distance provider.

1. In Japan, a government advisory committee called for the breakup of Nippon Telephone and Telegraph Company, the largest telephone company in the world, so it would be

2. The breakup of the world’s largest telephone company, Nippon Telephone and Telegraph Company, was called for by a government advisory committee in Japan, so it would be

3. A government advisory committee in Japan called for the breakup of Nippon Telephone and Telegraph Company, the world’s largest telephone company, into

4. The breakup of Nippon Telephone and Telegraph Company, the world’s largest telephone company, was called for by a government advisory committee in Japan, so it would be

5. Called for by a government advisory committee, the breakup of Nippon Telephone and Telegraph Company in Japan, the world’s largest telephone company, was to be into

A里的it就是犯了指代不清的毛病

为什么犯呢？，是因为只要前面出现了2个或2个以上的单数名次就一定指代不清吗？（them，they也这么判断吗？）

马上要去考了，期待NN的解答。

但是我明确这里it是Nippon Telephone and Telegraph Company

这样也是只要有两个以上单数名词就指代不清吗