Ifanythingshouldhappen,thenearestpersonhecouldcontactb...
来源：语文精选馆 1.11W
问题详情：
If anything should happen, the nearest person he could contact by radio , _____ there was a ship nearby, would be on an island 885 miles away.
A. until B. when C. once D. unless
【回答】
D
知识点：连词
题型：选择题
