题干
You will not be allowed to get into the plane_______ you pass security checks(安检).
A：if
B：unless
C：or
D：because
答案(点此获取答案解析）
B
You will not be allowed to get into the plane_______ you pass security checks(安检).
A：if
B：unless
C：or
D：because
④苯、水⑤已烷、水⑥环已烷、苯⑦溴苯、水
