问题
选择题
Our school _________ be an old shoe factory, now we ___________studying here. It is a good place to study.
A．used to , used to
B．is used to , are used to
C．is used to, used to
D． used to, are used to
答案
答案：D
题目分析：句意：我们学校曾是一座旧鞋厂，现在我们习惯在这里学习。这是一个好的学习地方。短语used to do过去常常做某事；used to be 过去曾是……; be used to doing sth.习惯做某事；结合语境故选D。
CaCO3↓+H2O
H2+CO