We can do this by defining a filter on the metadata to search for checkout records with a CHECKIN value of null.

为此，我们可以定义元数据过滤器来搜索checkin值为空的签出记录。

youdao

The second filter removes any list items where the left side of the expression is a primitive type or a null.

第二个过滤器负责移除任何表达式左侧为一个基本类型或null型的列表条目。

youdao

It can constrain frequency response of filter Banks to form null at zero frequency point and to obtain minimum side lobe area.

它可强制滤波器组的频率特性在零频形成零点并使旁瓣面积最小。

youdao