I forget to bring a pen, would you lend me ____?

The students were all tired, but ___ of them stopped to have a rest．

---Which of these shirts do you like best?--- I’ll take      . They are all expensive and out of fashion.

---Carl, why not go and help your sister water the flowers there?  ---Why__________? I’m busy myself. Jack is lying on the grass doing nothing.

The houses of the rich are generally larger than _______ of the poor.