题干
When people go on a trip, they like to brings some______ for their friends.
A：meat
B：gifts
C：bikes
答案(点此获取答案解析）
B
When people go on a trip, they like to brings some______ for their friends.
A：meat
B：gifts
C：bikes
的定义域为1，2，则
的定义域为（ ）