By the time she retired, she had been teaching math for 30 years.

[Alice Chu]

The two sentences below have the same meaning-the repeated action of teaching math lasted for 30 years until she retired.
The second sentence is better than the first one.
Is my understanding correct?

1. By the time she retired, she had taught math for 30 years.
2. By the time she retired, she had been teaching math for 30 years.

 

[tedmc]

The first sounds more natural to me.
Why do you think the second is better?

 

[jutfrank]

No, your understanding is not correct.

First of all, I don't think you can say that they have the same meaning. Why do you think we have two different forms if they have the same meaning? You should be looking to identify the difference in meaning.

Secondly, why do you think the second sentence is better than the first one. Has someone told you that or is it your idea?

Your goal here seems to be to identify the differences in meaning and use between present perfect simple and present perfect continuous. I don't think it's going to help you to do this by using the same context for your example sentences.

 

[Alice Chu]

(1) My understanding comes from the following examples.
The second example is more natural than the first one.
The two examples mean the repeated action of teaching English started 20 years ago and continues in the present.
1. A: How long have you taught English?
B: I have taught English for 20 years.

2. A: How long have you been teaching English?
B: I have been teaching English for 20 years.

(2) The following examples can tell the difference between the two forms.
1. He had played baseball every day for two years by the time he got hurt.
It means the repeated action of playing baseball lasted for two years until he got hurt. We can use “had been playing” here.

2. He had been playing baseball for an hour by the time I got there.
It means the single action of playing baseball lasted for an hour until I got there. We cannot use “had played” here.

Is my understanding correct?
Thank you very much for your help and patience.

 

[5jj]

1. A: How long have you taught English?
B: I have taught English for 20 years.

2. A: How long have you been teaching English?
B: I have been teaching English for 20 years.

The second is not necessarily 'more natural' than the first. It's simply that the speakers view the duration of the teaching in slightly different ways. In the first, they are perhaps focused more on the time period. In the second, they are thinking more of the ongoing duration.