All depends on the context of the sentence, but in general, one can assume the following: 1. The simple aspect of tenses imply: (state, fact) a) that the action is permanent b) that the action is finished "I have lived here for 9 years" could therefore imply: a) I have lived here for 9 years, I don't live here anymore and I want to emphasise that it is a rather permanent situation. b) I have lived here for 9 years. I don't live here anymore. I'm sad to be leaving today. 2. the continuous or progressive aspect of tenses imply: (stress on durational aspect) a) the situation is in progress, unfinished. b) the situation is temporary "I have been living here for 9 years", could therefore imply: a) I have been living here for 9 years, so my residence is still here, I still live here. b) I have been living here for 9 years, but I'm not really planning to stay here. This isn't permanent. The idea behind tenses and aspect is almost philosophical in nature, in the sense that one sentence written in one tense could be interpreted in many different ways. That's why I started my answer with stressing the importance of the context of the sentence. For instance, if I'm walking around with a friend and suddenly I say: "I hate this place, I have been living here for 9 years." This means I want to change something about my situation and so I stress that the situation isn't permanent by using the progressive/continuous aspect. Summary: Present perfect will always describe a general state (with non-specific time, e.g. yesterday or 5 pm --> that's for simple past), whereas present perfect progressive will always stress the durational aspect of the sentence. I hope this answers your question. Dennie

A native speaker wouldn't normally use this sentence, unless he or she has the intention to puzzle (surprise) their listener or reader. The sentence is grammatically correct, but it makes no sense. (semantically it isn't correct). This excerpt is from a book from Shonda Rhimes and later on in an interview she explains what veal practice means to her. “Veal practice,” as Ms. Rhimes wrote, “involved me lying very still on the sofa trying as hard as I could to mimic the life of a veal. While eating veal.” Weird? I know, but then again, that's the explanation there is to this "mystery sentence". One could continue in the line of Ms. Rhimes: practice crab, practice monkey, practice frog, ... ;-) Hope this helps.

Here's how I would rewrite these sentences: 1. If you want to, we can help you improve your English. or If you are worried, we can help you improve your English (but this seems a rather weird sentence). 2. We last saw Tom December 2010. Hope this helps.

"Thank you for keeping struggling." is not correct, but I am not sure what the meaning of the sentence should be? I first thought: "Thank you to keep on struggling" (but that sounds or seems rather weird). I agree with what Michael Chambers said in his message and I assume his sentences are what you wanted to say with your sentence.

Interesting question. I am not sure whether my answer is completely correct, but here's my reasoning. a) Let's simplify things: Companies can't afford to give away more discounts and incentives than is absolutely necessary to retain a customer. b) Let's seperate phrases: companies // can't afford // to give away more discounts and incentives than is absolutely necessary. S V DO to retain a customer. In this sentence, of course companies is the subject (S), can't afford the verb or verb phrase (V) and the rest of the sentence is direct object (DO) c) let's simplify again to give away more discounts and incentives than is absolutely necessary. It must be clear by now that this sentence on its own doesn't make sense (it is not a complete sentence), therefore, you're not anymore trying to find the subject of the main sentence, but one of a complementary sentence. You can see this because of the "more than" that is used in the DO of the main sentence. In this particular case, I think, there is an implied "it". Maybe this becomes clear if I rephrase the sentence and d) make it a main phrase: It is important (necessary) to give away no more discounts and incentives than absolutely necessary (to retain a customer). With this rephrasing it's clear that "it" is the subject of the sentence. Because we left out "can't afford", there are some changes if we make this our main sentence. - can't afford --> has to be made clear in sentence by saying "NO more discounts..." - repetition of necessary/important is required, else the new sentence wouldn't make sense. e) the "is" in this sentence could probably be left out (hence, no subject needed). Companies can't afford to give away more discounts and incentives than absolutely necessary to retain a customer. In conclusion: - There is an implied subject (it) in the complementary sentence. - the "is" in this sentence could probably be left out

You should look into the subject of the difference between to look, to watch and to see. Look --> requires effort; e.g. I'm currently looking for a job. See --> doesn't require effort, happens spontaneously; e.g. we were walking down the street, when we saw the accident. watch --> pay very close attention (especially for change); e.g. I've been watching TV all night. combined in example sentence: If you watch the neighbours long enough, you'll see that they've been looking for the treasure in the garden. If you watch (pay close attention) the neighbours long enough, you'll see (happens spontaneously, doesn' t require effort) that they've been looking (requires effort) for the treasure in the garden. Hope this helps.