I wonder if the landlord has found the answer himself. I want to briefly talk about my views, which may not be correct, but discuss them with each other for better understanding.

In "Tutorial" 4.3.3, firstly, the "object" is defined, namely:

Object is also a difficult term to define. Traditionally, the subject can be defined as the executor of the behavior, so the object can refer to the "receiver" or "target" of the behavior, and is further divided into direct object and indirect object.

Then he said:

Modern linguists (such as Chomsky and Halliday) believe that an object refers to such an item, which can become the subject of passive conversion.

So, naturally, go on:

Although there are noun phrases in ex. 4-27, they are by no means objects, because they can't be converted into passive voice.

Exodus 4-27

He died last week.

The game lasted for three hours.

He changed trains in Fengtai. He changed trains in Fengtai. )

Say my own opinion: if he changes trains according to the above definition, I will definitely think it is object, because as a supplement, I am not used to it. After all, this is very different from (a) and (b). However, the object is, after all, the receiver of the action, and this sentence can not be said that the train suffered a change of direction, but can be understood as that he changed his route by taking another train. Just as we can't understand "spring" as an object in Chinese, it seems to be a verb+noun structure. Is the "spring" a dynamic compensation structure? I don't think so. So sometimes free translation and structural analysis will conflict.

In 4.3.4, the tutorial mentions this example again, and says it is a verb+complement structure, which is based on whether English sentences can become passive or not. In 4.3.3, it is also explained that this is based on the views of some linguists (Chomsky and Halliday). Therefore, whether individuals can accept it or not varies from person to person.

But I don't think it is appropriate to define it as complement. Because the definition and characteristics of complement are not given in the tutorial, it is bound to be controversial to regard the above sentence as "verb+complement"

I hope I can help you, and welcome further discussion.