"I lived here" is a competed action in the past. It has no affiliation to the present and so would be past/perfect tense.

e.g. "I lived here once upon a time" or "I lived here 6 years ago" (not anymore)

Whereas "I have lived here" is a present perfect tense as it relates to the present and is an ongoing action.

e.g. " i have lived here since 2010" (still living there) or "i have lived here for 3 years" (still going)

I lived here = Past simple, e.g I lived here 10 years ago. You use it to provide a statement of fact, or habitual statement, but in relation to the past.

I have lived here = present perfect, used to expressed something that started in the past but still happening. see above from Bea.

That doesn't sound right to me. I would use the passé composé:

Je n'ai pas quitté la France depuis trois ans. -- I haven't left France for three years.

The first sentence seems ok to me. In the second sentence I would use the present tense, indicating that the lake has started to shrink in the past and is still continuing now: Depuis quelques années, le lac diminue.

Doesn't that contradict what's said in the lesson below?

Using Le Passé Composé or Le Présent in negative sentences with ''depuis''

I think you're right Alan.  I hadn't seen that lesson.  My sentence does use "ne...pas", which according to the lesson you cited requires Passé Composé.  

This might look like a passé composé on first inspection but it actually is present tense passive voice.

ah yes, I see now! I thought it was se marier at first. ok that makes sense now, but I wonder if a specific example should be included or if another tense/voice should be mixed in the example as it is confusing. I’m going in order from A0 onward and haven’t encountered a lesson on passive voice

Hi William,

I think you may be confusing the usage and depuis and puisque which both can be translated in English as since, but with different meanings:

Depuis (preposition) since, a marker in time ,  puisque, (conjunction) since, because

So your sentence would become :

Puisque je reste à Lyon avec ses parents, mon ami vit dans mon appartement à Glasgow.

Yes, there is no reason why you cannot start the sentence with  puisque.

I apologise if I have misunderstood the meaning of your question.

Pendant, in this context, refers to a well defined period in the past. Therefore I would say:

J'ai étudié  le français pendant deux ans.

I don't think there is a rule forbidding the use of imparfait in conjunction with pendant. It's just that in this example, I would use the passé composé.

The opinion of a native speaker would be greatly appreciated, though.

Can we use l'imparfait with pendant? 

Hi Sagar,

s'habillaient is the imperfect, se sont habillés would be passé composé. 

-- Chris. 

Thank you, Cécile and Chris.

I understand now. It really comes down to the idea that l'imparfait should be used when describing an ongoing action in the past. I was under the impression that l'imparfait was only required for the first part of the answer ("j'etais"), while the passé composé could be used for the second part.

It's clear now. Thank you so much.

I love Lawless French.