有效数字是指（）准确数和（）位欠准数的全体。实验结果的表达式中测量值的末位应与（）所在位一致（或“对齐”）。
参考答案：几位；一；不确定度
The last thirty years _____ the greatest number of laws stopping our rights and progress. Until today we have reached a stage _____ we have almost no rights at all.
A．saw; which
B．see; where
C．are seeing; in which
D．have seen; where
冬季原油线停用后，要及时（）干净，以防冻凝.
