The chairman thought       necessary to invite Professor Smith to speak at the meeting.

Grandma will appreciate ____ if her elder sister could come back from abroad.

 –Did you buy _______ for yourself?  --No, I bought ________.

I had no idea ____ is better, so I took ____ of them.

---Are the Smiths living in the house alone ?--- Yes, although they have three sons, _____ of them live with their parents.