— I haven’t finished my task yet.

— You shouldn’t have watched the film last night, or you _______ it by now.

A, need have finished                       B. may have finished

C. should have finished                    D. will have finished

对于较短的真空间隙，当真空度在1.33×10－1.33×10 Pa之间的变化时，击穿电压随着真空度的变化而变化。