根据《液压爬升模板工程技术规程》，爬模装置的制作中，导轨平直度的允许偏差是（）mm。
A.2
B.±2
C.±3
D.±5
参考答案：A
I don't remember _____ the boy by himself. [ ]
A. why did she leave
B. why she left
C. why had she left
D. why she had left
如果等风险债券的市场利率不变，按年付息，那么随着时间向到期日靠近，溢价发行债券的价值会逐渐下降。 ( )
