[Grammar] past tense? past perfect?

[je2ks2]

Here is a passage I've got for grammar test today.

The English language develop out of Germanic dialects that were brought to Britain during the course of the 5th and 6th centuries by Jutes, Angles, and Frisians. By medival times, this Germanic language replace the original Celtic language of Britain in nearly all of England as well as in southern and eastern Scotland.

The question was to change the underlined verbs into the correct form. The answer was 'developed' and 'had replaced'. Yet, I am pretty confused with those answers.

I think we use present perfect when refering to the event which lasts for some duration of time as in (1) and (2)
(1) I have been here for 10 years.
(2) There has been a general increase in permafrost temperatures during the last several decades in Alaska

My assumption is that for during the course of the 5th and 6th centuries refers to some duration-100 years, past perfect could be more appropriate than past tense. I think past tense can be used only when we say a specific time or moment. I know my assumption is wrong. That is why I am asking you for help.

Anyway, I don’t still know why those two verbs above the passage should be changed into ‘past tense’ and ‘past perfect’ respectively.
Would you explain to me why? I am not sure if I get my point across. (Sorry for my poor English. English is very challenging to me when it comes to tense.)

Your help will be really appreciated. Thank you so much in advance.

[David L.]

The English language develop out of Germanic dialects that were brought to Britain during the course of the 5th and 6th centuries........

The main part of the sentence is:
The English language developed out of Germanic dialects.
This happened long ago in the past, so past tense.
(The rest of the sentence adds further information).

during the course of the 5th and 6th centuries ... By medieval times, this Germanic language had replaced the original Celtic language.
'by' indicates the end of a particular time period, that period being from 6th century, to Medieval times. So, we are discussing something that happened totally in the past, over a time period. The tense we use is Past Perfect.

[Graver]

Originally Posted by je2ks2

Here is a passage I've got for grammar test today.

The English language develop out of Germanic dialects that were brought to Britain during the course of the 5th and 6th centuries by Jutes, Angles, and Frisians. By medieval times, this Germanic language replace the original Celtic language of Britain in nearly all of England as well as in southern and eastern Scotland.

The question was to change the underlined verbs into the correct form. The answer was 'developed' and 'had replaced'. Yet, I am pretty confused with those answers.

I think we use present perfect when referring to the event which lasts for some duration of time as in (1) and (2)
(1) I have been here for 10 years.
(2) There has been a general increase in permafrost temperatures during the last several decades in Alaska

My assumption is that for during the course of the 5th and 6th centuries refers to some duration-100 years, past perfect could be more appropriate than past tense. I think past tense can be used only when we say a specific time or moment. I know my assumption is wrong. That is why I am asking you for help.

Anyway, I don’t still know why those two verbs above the passage should be changed into ‘past tense’ and ‘past perfect’ respectively.
Would you explain to me why? I am not sure if I get my point across. (Sorry for my poor English. English is very challenging to me when it comes to tense.)

Your help will be really appreciated. Thank you so much in advance.

By medieval times, this Germanic language had replaced the original Celtic language of Britain in nearly all of England as well as in southern and eastern Scotland.

This sentence suggests that the Celtic language already fell out of use or died out just before the Middle Ages. The Past Perfect is used here to emphasize that it happened BEFORE the medieval era. The C.L. was NOT used any longer at the time. Whenever you find a construction "BY THE TIME..." and you're to use a past tense it's best to use the Past Perfect. As to the first sentence... I think there's no need to use the Past Perfect here. The verb "to develop" may imply continuity or process taking place over a period of time - true. The process definitely took place in the past but there's no mention of it having taken place before anything else. Why bother with the Past Perfect?

I know my explanations might seem a little nebulous but I hope I helped you understand the problem better.
Wait for some other guys to reply since they know how to explain grammar better than me.


Graver