1.The history professors were dealing wih these in historica

1.The history professors were dealing wih these in historical _____?
A.sequence B.sccession C.series.D.success
2.It is essential that he _____ extracurricular activities.
A.will participate B.participates C.participate D.shall participate
3.He talked as if he ______ the incident.
A.had witnessed B.witnessed C.witness D.have witnessed
4.Frankly speaking,I'd rather you _____anything about it for the time being.
A didn't do B.haven't done C.don't do D.have done
这几题是我做错的,希望能给我讲解一下,