Gun control is the subject ________ Americans have argued for a long time.

The case is rare ______ a man can be cured of such a terrible disease.

“Ungelivable” is so new an English word coined on the Internet ______ is forbidden to appear in official media or documents at present.

All the neighbor admire this family. _________the parents are treating their child like a friend.

I will never forget the day _____  we worked together in London．

I often read China Daily, ____of great help to my English study.

The old lady had a son and two daughters，________treated her well，which made her very sad.

Bears often hide themselves in places ________ can’t be found by hunters.

Watch out! Don’t get too close to the building         walls are being painted.

Saving money is ________ we must do.