What tense should I use?

[usignolo]

It had been raining two days running or it was raining two days running.

Thanks in advance,
Max.

[bhaisahab]

It had been raining two days running or it was raining two days running.

Thanks in advance,
Max.

It could depend on context, but I would prefer "It had been raining..."

[usignolo]

It could depend on context, but I would prefer "It had been raining..."

Could you explain me the difference between the past perfect continuous and the past continuous. If you can, use this example with rain, please.

[bhaisahab]

Could you explain me the difference between the past perfect continuous and the past continuous. If you can, use this example with rain, please.

It was raining when we arrived in London, it had been raining for two days running.

[usignolo]

Thanks a lot.

[usignolo]

By the way, is it necessary to put the preposition for in this sentence?

[bhaisahab]

By the way, is it necessary to put the preposition for in this sentence?

I think so yes, some may disagree.

[usignolo]

Thanks again.