It would depend on the context. You cannot use a structure from English/Russian in German, there might be a difference in meaning. Dieses Problem ist zu diskutieren. Meaning: This is a problem we have to discuss before making a discussion. The one who said that might think that the other person has an opinion which he does not share. Ich habe ein Buch, dass ich gerade lese. I have a book which I read at the moment. Ich habe ein Buch zu lesen. That is rather uncommon or it would mean that I have a book which I have to read.