Hugo V.: I have doubts about using the comparatives, e.g. yellower, redder.

MP: Hello Hugo - comparatives. The simple rule is that if the word has one syllable like 'small', 'cold' we add 'er'. So it is fine to say 'redder than'. With words of three or more syllables like beautiful, intelligent we can't add 'er'. So we say 'more beautiful', 'more intelligent'.

The problem as you've spotted comes with words that have two syllables like 'yellow'. In these cases I'm afraid it just depends on the word. By the way, to say something is yellower than something else is grammatically fine but I wonder what you are talking about?

We normally compare qualities which have different degrees. Example: We can have many different degrees of 'big'. Absolute qualities on the other hand, like 'dead', 'alive' and perhaps 'yellow', we don't usually compare.

Moohyun S.: What kinds are there of 'if' mode?

MP: Hello Moohyun - I guess you're asking about 'if' in conditional sentences. Traditionally, we think of there being four types. In reality we mix these up and often break the rules. Do try to get hold of a good grammar book.

Davood from Iran asks: Could you tell me what defference between 'another' and 'other'is?

MP: 'Another' refers to only one thing. You may find it helpful to think of this as two separate words 'an' and 'other'. We say 'Can I have another cup of tea?' meaning just one more. 'Other' refers to more than one. For example, 'I have vistited France and many other countries in Europe'.

Duong Van Quynh from Vietnam asks: Would you please explain me the difference in the meanings of these two sentences: "I am to meet the boss." "I must to meet the boss."

MP: Now let's see - 'I am to meet the boss' means that someone else has organised my programme and a meeting with the boss is part of this programme. 'I must to meet the boss' actually has a little mistake in it. After 'must' we use the infinitive of the verb without 'to'. So this should be 'I must meet the boss'. The meaning of this is different. In this example, I am telling myself or persuading myself to do this.

Hugo V.: What is the difference between using 'would' or 'used to' to refer to past events?

MP: Very good question and well spotted! We can use 'used to' to refer both to habits and to states in the past. Example: 'I used to get up early' (habit). 'I used to be spotty' (state).

'Would' on the other hand can only refer to habits and never to states. So, we can say 'I would get up early' but we can't say 'I would be spotty'.

Orhan Serttas: How can we know which noun is countable or uncountable? Is there a rule?

MP: Most nouns are either countable or uncountable. It is logical which is which. For example, clearly we can count books so the word 'book' is countable. On the other hand, we can't count 'water' so the word 'water' is uncountable. Unfortunately, though there are a few words where this distinction isn't so clear. 'Furniture' is a good example of this. We can't say 'I bought some furnitures' because 'furniture' is uncountable. However, lots of learners of English think (rightly!) that this is rather illogical.

Tang Calvin: Hi Martin, what about money?

MP: Tang - 'money' is an excellent example. We count pounds, dollars and RMB. So we can say 'five pounds'. Money is uncountable so we can only say 'a lot of money'.

Roze from Iran asks: What is the difference between 'so' and 'such'?

MP: We use 'so' before an adjective, for example: 'so tall'. We use 'such' before an adjective followed by a noun, for example: 'Such good questions'. The meaning of these two words is very similar - it's just the grammar that is different. Remember that usually we use both of these words before a clause which explains the consequence. Example: 'It was so interesting that I fell off my chair!'

M.Sharif Azizi from Afghanistan asks about types of adverbs in the English Language.

MP: We have adverbs of frequency, like 'always', 'never' and 'sometimes'. Secondly, we have adverbs of manner which tell us 'how' something is done. Example: quickly, carefully and neatly. As you can see these usually end in an 'ly' but be careful because there are a few exceptions.

Then we have adverbs of time and place like 'then', 'now', 'tomorrow', 'here'. We have adverbs of degree like 'very', 'fairly', and 'quite'. What is a bit confusing about adverbs is that people call any word an 'adverb' if it doesn't really fit into any other group.

Ivan from Canada asks: According to the English grammar, the article "the" is not used with the name of a coutry. Why sometimes some people write "the Ukraine" and others just "Ukraine"?

MP: As you probably know, a small number of countries have 'the' in their name, usually if it is plural like 'the Netherlands'. Or if it is followed by a word like 'Republic' - 'the Czech Republic'. But, I think your example is a bit different. Since Ukraine became independent just about 13 years ago, we have begun calling it Ukraine. We used to call it 'the Ukraine' and as you know over the last few centuries there have only been very few years during which the country was independent.

Sheng Chai asks: Dear Martin, I wonder what's the difference between present perfect & past?

MP: Present perfect and past - we use the present perfect when we are interested in the event, and the time it took place is unimportant. If we mention the time - or even if we understand the time but don't mention it, we use the simple past. Example: We say 'I went to Malaysia in 1990' but we say 'I have been to Malaysia' if this is just a fact about my life.

Zora from US asks: what is difference between public and universal?

MP: Zora - we use 'public' when there is no secret involved. It isn't necessary for a lot of people to know about it, but we don't care if they do. Example: 'I made my marriage public. I told some people that I was married'. 'Universal' is very different. It means that everyone knows about it.

Hafiz from Afghanistan asks: My problem is that I am not clear how to recognise verbs, nouns, adjectives in sentences. How can I recognise them easily?

MP: Most of the time, we can't tell just by looking at the word what type of word it is - adjective, noun etc. There are a few exceptions to this however, for example words that end in 'ion' are almost always nouns: 'station' 'television' 'question'. And words which end in 'ful' 'ous' or 'al' are nearly always adjectives: 'careful', 'vicious' and 'musical' are all adjectives.

However, we really recognise them from their position in the sentence - what other words we find around them. Remember though, don't worry too much about what type of word any word is. The important thing is to recognise and understand what it means.

However, a new scheme is being introduced at the moment for people studying science, maths, or technology, you will be able to stay in the UK to work for a year. If you are a student from the EU this is not an issue, as you are able to work across the European Union.

Sheng Chai asks: What about the word order for adjectives?

MP: When we use several adjectives together we usually start with the most general and work towards the most specific. Example: 'I read a good, interesting, old-fashioned, 18th century book'.

Davis from China says he finds English grammar hard because it is different from Chinese grammar.

MP: Your question is especially interesting for me because I am a student of Chinese language! I wish I knew the answer Davis! I find reading is the most helpful way of becoming familiar with the different grammar. I often think the real problem is that the information is ordered in such a different way, isn't it? I know this is old-fashioned but it seems to me when we get stuck we need to try dividing up the sentence into grammatical units and of course translation helps here. But, this is a difficult problem I know.

Hugo from Colombia says: I would like to know the difference between some confusing words in English such as: hit, punch, strike, beat - and garbage, rubbish, trash, waste, litter.

MP: 'Punch', 'strike' and 'beat' are all examples of hitting. We call 'hit' the super ordinate because it is the umbrella word. 'Punch', 'strike' and 'beat' are hyponyms, in other words they are more specific examples of hitting. We use 'punch' when we close our fist and directly push it forward fast. We use 'strike' when we hit someone with the side of the hand or with another object. And we use 'beat' when we hit someone or something repeatedly.

Your other example is to do with dialect and register. 'Garbage' is American English and 'rubbish' is British English. Both words are neutral. 'Trash' is also American but is more informal than 'garbage'. We use 'waste' to refer to industrial processes and we use litter just for paper. Of course there are one or two exceptions, for example we say 'wastepaper basket'

Remember that listening to BBC English programmes will also provide lots of answers to your questions and give you some ideas for new ones too.