Compléter UNIT 7 WRITING 6THVersion en ligne Complete the sentences using the words in parentheses. par Douglas Rivera 1 1 . Diana Northup has curiosity . She wants to know about life in this cave . That means the cave ( must / visited ) . Caves are dangerous places , and some risk ( have to / taken ) . Northup is always careful . 2 . She knows the dangers . For example , Northup knows that the air in this cave is poisonous , so she uses a gas mask . The cave ( mustn't / enter ) without a gas mask . 3 . Northup knows that the level of gas goes up and down . When it goes up , it is extremely dangerous . That's why a gas meter ( have to / use ) . With this , the gas level ( can / checked ) while she is down there .