I understand you all along.
No. The correct way is: I've understood you all along.
No - the sentence 'Had never been experience' is not a correct sentence.
No, that sentence is not correct. That sentence should be: If you have been in love for 6 years.
The correct sentence would be "He could not have been there". This is because 'can' is in the present tense and doesn't agree with the rest of the sentence.
No. They (the rocks) would not be moving past each other if their movement had been permanently halted.
Being able is the correct version of the sentence. You can use it as a fragment of any sentence.
The correct sentence is: "Have you ever traveled before?"
A central fund for EGMM has been opened.
Yes, "How long have you been living in Oxford?" is a good sentence.
The use of the word in the sentence you quote is in the sense of having been perceived as being rude to an elder. So yes, the sentence is correct.
Your account has not been generating much traffic.This sentence is grammatically correct. It is negative present perfect continuous.
Yes, the grammar in the sentence "The attached invoices have been confirmed" is correct.