问题
选择题
Because of too many differences between the two sides, a lot of questions are still left ________.
A in the air B on the air C by the air D through the air
答案
答案：A
本题考查词组搭配。In the air 意思是“（计划等）未决定的”；on the air 意思是“在广播中”；C、D不正确。根据句意“很多问题还未解决”，故A正确。