Thankyou, verse 4:20 has nothing to do with 4:1,2,3 , as I see. I referred to 4:2o under the discussion of "Multiple Marraiges", because it says وان اردتم استبدال زوج مكان زوج , the replacement of "one" with "another", not "two-together".
Under this topic, I referred to it, because I'm not clear, why Allah Almighty has "allowed" the replacement of wife with a wife, and not husband with a husband, on the contrary. If you can kindly enlighten me of your view.
Thanks for explaining 24:3. (I used my daughter's computer without paying attention to her account , yesterday. I apologize for inconvenience.)