1.It's suggested that each one of us___the training classes

1.It's suggested that each one of us___the training classes for English.
A takes part in B take part in C took part in D would take part in
2.The only thing___interests me is the progress of my students.
A what B that C which D it
3.If there were no homework at weekends,students would have___at home.
A the happiest time B much happiest time C a more happier time D a much happier time
4.The reason he won the election is___he is honest and confident of himself.
A why B what C that D which