信度分析时出现warnings：
The determinant of the covariance matrix is zero or approximately zero. Statistics based on its inverse matrix cannot be computed and they are displayed as system missing values.

这时的信度结果还可以使用吗？

部分条目的Corrected Item-Total Correlation偏低，介于0.071~0.356，这是什么原因？如何处理？