and, at last, 'whose'. 'Whose', as well, may be used to make a question or not. It indicates inheritance or possession of someone spoken of or tried to be known. e.g. "Whose is this car?" (You're trying to know the owner of the 'car') "Whose are these children?" (You're trying to know the parents of the 'children') "Whose is all this bravure?" (You're trying to know the person that has 'all this bravure') "President Roosevelt, whose name will always be remembered, is now dead" (You're indicating that the 'name' belongs to 'President Roosevelt'. It is a part of him.) "The policeman, whose pistol is always ready to open fire, is now fired." (You're indicating that the pistol belongs to the policeman, he possesses it.) I hope I could help you. Any remaining doubt, I'm here.

'Which' is easily understood if you know how to use 'what' properly. The main use of 'which' is to know something (person, animal, object, etc.) from a group of these things. e.g. 'What is this thing?' (You ask this when you simply wish to know the 'thing'.) 'Which is this thing?' (You ask this when you wish to distinguish this 'thing' from the others of the group.) 'What is that fast vehicle?' (You ask this when you simply wish to know the 'fast vehicle'.) 'Which is this thing?' (You ask this when you wish to distinguish that 'fast vehicle' from the others.) As you discover the uses of 'what', probably you'll discover the uses of 'which'. I just said one.

OK, next part. 'Whose', 'which' and 'who' are pronouns too. Commonly, interrogative pronouns, i.e., you use them when you wish to make a question. 'Who' is the easiest. It may only be used when talking of people or something (animal, object, etc.) made as it. e.g. 'Who is talking to her?' (Who, here, is used to know the person that is talking to the other, the female one.) 'Who is the daddy's puppy?' (Who, here, is used by the owner to know the puppy) 'Who is that wind, flying so elegant and unconcerned with us, mortals?' (Who, here, is used to know the wind that is flying - Limited to poetry) etc. Who, also, can be roughly used to replace 'that' as a relative pronoun. e.g. "The guy that is next to me." "The guy who is next to me."

Hi Sayed, 'Those' is one of the demonstrative pronouns in English. They are used to specify the subject. It is not anyone, but 'this guy' or 'that guy', etc. 'This' and 'that' are the most common and their difference stands on the former being used to something close in time/space and the latter to something more distant in time/space. 'These' is the plural form of 'this' and 'those' is the plural form of 'that'. e.g. "This guy (the one here, next to me) is really boring." "That guy (the one there, more distant) is really cool." "These guys (the ones here, next to me) are really boring." "Those guys (the ones there, more distant) are really cool." You can also use 'that' as a relative pronoun, refering to something already spoken of. e.g. "The guy that is boring is next to me." "The guy that is cool is distant to me." But you can't, as a general rule, use 'this', 'these' or even the plural of 'that', 'those', as a relative pronoun. Wrong: "The guy this is boring is next to me."; "The guys these are boring are next to me."; "The guys those are cool are distant to me."