某分部工程双代号网络计划如下图所示，则工作D的总时差和自由时差分别为（）天。

A.1和1

B.1和2

C.2和1

D.2和2

Quality planning tools are often used to help plan effective quality management activities.（）is one of such tools,which involves comparing actual or planned project practices to those of other projects to generate ideas for improvement and to provide a basis by which to measure performance.

A.Benchmarking

B.Quality metric

C.Quality checklist

D.Brainstorming