问题
选择题
In my opinion，life in the twenty－first century is much easier than ________.
A．that used to be
B．it is used to
C．it was used to
D．it used to be
答案
答案：D
表示 “过去常常……”用“used to do”。本题中“be”为连系动词，不是实义动词，不能省略。
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