当建筑物残值( )时，建筑物的损耗率和成新率之和等于1。
A．大于零
B．等于零
C．小于零
D．小等于零
参考答案：B
Not until I began to work ________ how much time I had wasted.
A．didn’t I realize
B．did I realize
C．I didn’t realize
D．I realize
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