China has opened its _______Antarctic research base (南极科考站) – the Taishan Station.

Is this Tom and Sam’s room– No , it’s ours. _________ is on the fifth floor.

When I heard my baby girl say her first word , my heart was of joy.

He insisted that the company ________ immediate action to solve the problem. [ ]

It is generally believed that ______a piece of field is, ______ it produces.[ ]