计算题：将30×1.4的管材拉制成9.52×0.7mm，延伸系数是多少？
参考答案：
延伸系数计算公式：
下列叙述错误的是( )
A．用新制的银氨溶液可区分甲酸甲酯和乙醛
B．用高锰酸钾酸性溶液可区分己烷和3-己烯
C．用水可区分苯和溴苯
D．用金属钠可区分乙醇和乙醚
24. In their hearts, some children think it is their parents’ business to earn money and________to spend it.
A．they
B．them
C．their
D．Theirs
