What is right?

How do I say and why:
Christopher promised he would help me until he......back
a)comes
b)came
c)will come
d)vould come

[Tomasz Klimkiewicz]

Hello, Henrieta and please allow me to contribute with my two cents.

First of all, I think the usage of 'until' in the example you gave is incorrect. If I understand the sentence correctly 'as soon as' would be more appropriate.

The tenses appearing in the clauses of the example are determined by the relevant principles of the reported speech:

Christopher: 'I will help you as soon as I come back".

Now you report his words like this:

Christopher promised (Past Tense) he would help me as soon as he came back. (A direct consequence of the opening phrase in the Past Tense)

Well, that's in my humble, non-native speaker's opinion, of course.

A sentence with a similar meaning and still using 'until' would be

Christopher said he wouldn't be able to help me until he came back.

To more experienced users: please correct me if I'm wrong. It's not going to be a devastating blow to my pride. After all, most of us are still in the process of learning. Thank you.

T. K.

[Wai_Wai]

Hi, everybody.
I am also a learner.
I'm going to give my two cents worth.

If I make any mistake, please feel free to criticze me.

Tomasz Klimkiewicz is right the word "until" is used wrongly.

"he would help me until he came back"

That means he would be available and help you from now to the time when he came back. After he came back, he would not help you. I'm afraid it will never be correct except for jokes.

His alternative is correct. Another one you may use is "when".

Back to your question, it is a question about reported speech.

Christopher promised he would help me until he......back
a)comes
b)came
c)will come
d)would come

Since the sentence uses past tense, so answer (a) and (c) must wrong.

This leaves only (b) and (d).

You may think, since the case of "his return" has not realised yet, so we should use "would come". It is true but partially. The answer should be (b) came.

There is tense simplification in subordinate clauses. Subordinat clauses refer to the clauses which is not the main/parent part of the statement.

So if the main verb of a sentence make sit clear what knid of time the speaker is talking about, it is not necessary for the same time to be indicated again in the subordinate clauses. It is also used to make the sentence neater and less clumsy.