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

—Mum, Where’s my______ shoe? I can’t______ it. —It’s under the desk.

 After a talk with his mother, the little boy has seen to _____ that the same mistake doesn’t happen again. 

---Does she study French, or German? ---She studies ___ of them.

We can’t believe that he drew such a big conclusion according to he took___ for granted（想当然）.