单项选择题
The scooter(滑板车) has been popular ______ a lot of children since the year before last.
单项选择题 This area is famous ______ its apples and it is famous ______ the home of apple.
单项选择题 Don't be anxious ______ her safety, she'll be OK.
单项选择题 Mr. Jackson devoted himself ______ teaching in the primary school.
