I don't want the explosive, every time when I become terrorist. There should be turn of every player to get the explosive. Is there a way to do that?
Its randomly chosen who gets the bomb. There is a very absurd, but tactical solution to pass the bomb by dropping it (G is the default key) directly to another player's body. It can also be a tactical solution to pass the bomb when you are in a combat and there is a player next to you (give the bomb to the player to be assured that he can carry it to the bombsite safely).
Players don't take turns who gets the bomb, unless they choose to do so. At the start of each round the bomb will be given randomly to a human member of the Terrorist team and there's nothing you can do about it (bots won't be chosen).
If you don't want it you can still give it to another player. This also counts for them. Some people have the habit of giving the bomb away all the time which would increase the chance of you ending up with it.
In certain tactical situations people may as well drop the bomb somewhere hidden near their attack point to not give away the bomb's location to the CTs when they're in combat, since you can actually see who carries it (they have it visible on the back as of CS:S or in a backpack in CS).