She is explain new grammar material now - настоящем времени 4 предложения She was explaing... - в прошлом времени She

1) She is explaining new grammar material now.

She isn\'t explaining new grammar material at the moment.

Who is explaining new grammar material now?

What is she explaining now?

Is she explainig new grammar material? 

2) She was explaining new grammar material when I came in.

She wasn\'t explaining new grammar material when I came in.

When was she explaining new grammar material?

She was explaining new grammar material, wasn\'t she?

What was she doing when I came in? 

3) She will be explaining new grammar material this time in a week.

She won\'t be explaining new grammar material this time in a week.

Who will be explaining new grammar material this time in a week?

What grammar material will she be explaining this time in a week?

Will she be explaining new grammar material or revising the previous one?