Ret fejl (Grammatik)

Det skal være 

"She has travelled to London to meet her old friend."

"20 years ago, he went to Australia to work."

#1

Det skal være 

"She (has travelled) went to London to meet her old friend."

"20 years ago(,) he went to Australia to work."

"She travelled to London to meet her old friend."

"He went to work in Australia twenty years ago."

#3,

Semantically speaking  "travelled" is somewhat too rich, -in a way superfluous here. There's no need to stress the act of travelling or the circumstances included in being on a journey. He just got to London, -one way or other    ......on a child's scooter, on a magic carpet,  a flying saucer   -whatever.

I know you're a native speaker, but still...............

as travelled is used in the original sentence it makes perfect sense to use it in the correction. If it had been she flew or she drove to london, then this should be used again in the correction and therefore its best to use travelled again. The problem in the first sentence is the extra word 'is' .

I very much disagree.

A literal translation would have been  "She has gone to London....."

There would, in this context,  be no point in saying "She journeyed to London to meet....." would there ??

That would correspond to saying "She travelled to London...".

The point is that she somehow got to London; it's not a question of describing all the discomfort, fatigue, unpleasantness or time spent or whatever which is characteristic of  being on a journey.

The verb is here quite empty, meaning nothing more than "move" or "change places".

The word to "travel" describes the act of travelling with all its implications, -not just "change of location"

I dare say that the whole point of the exercise was not so much semantics as it was to underline how Danish uses —in this context —'at være' as auxiliary verb in the present and past perfect tense of 'at rejse' ('hun er / var rejst ...'), whereas English uses 'to have'; ('she has / had travelled ...').

You will observe the same difference in meaning between "close the door" and "shut the door".

"close" describes the action", "shut" the result. You shut the door (=get the door to be shut) by closing it.

a)  He closed the door gently

b) He shut the door to keep the cat out.

"You want to go to London tonight and meet your friend ??  well, then you must find the quickest way of travelling".

With the verb "travel" the starting point and the destination are not af great interest. The activity in between is.

The problem seems to arise from the fact that in Danish the verbs "rejse" and "rejse" are really hononyms.

"homonyms"

ad #7,

In Danish and English the auxiliaries "være" and "be" are used in connection with verbs of movement and of change.

Cf. the difference between "she is gone" and "she has gone" and

"Hun er rejst" (=hun er væk)  ........change and "Hun har rejst (meget i Afrika)"  ..activity.

as far as I can see, this isn't an exercise in translation, just a  correction of two english sentences.

Of course it is an execise in translation -and as such in getting the most precise English rendering of the meaning intended.

In Italian they say "traduttore - traditore"      .......that is "a translator is a traitor".

The sources of error should be eliminated as much as possible, and your suggestion is not spot on, I'm sad to say.