A-A+
This region ______as the costliest place to do
问题详情
This region ______as the costliest place to do business.
A．often is referred
B．is often referred
C．is referred often to
D．is often referred to
参考答案
正确答案：D
解析：Adverbs of indefinite frequency can appear between the auxiliary and the main verb. Choices (A), (B), and (C) are not appropriate positions for indefinite frequency adverbs.
