frequent的否定前缀
frequent的否定前缀infrequent 很少见；
frequent
adj.频繁的;经常发生的；
v.常去，常到(某处)
We met in a local bar much frequented by students.
我们在学生经常去的一家酒吧里相遇。
There is a frequent bus service into the centre of town.
She\'s a frequent visitor to the US.
她经常去美国。
He is a frequent visitor to this country.
他常常访问这个国家。