How do you change the following sentence to the past tense?: The train is reaching its destination.
It depends on which past tense you want.
The train reached its destination.
The sentence given is in Present continuous, so, perhaps the best answer is:
The train was reaching its destination.
We could also use
The train had reached its destination.
Past perfect continuous:
The train had been reaching its destination.
I'm not sure where the sentence:
The train has reached its destination
fits into this system.