6) It's hot here Let's open the windows,
7) My brothers were
busy to help me to clean the house, so I did it myself.​

Ican show you an interesting picture of the city.can you  show you an interesting picture of the city? .i cannot show you an interesting picture of the city. he can give you his report on the life of jack london.can he give you his report on the life of jack london.? he cannot give you his report on the life of jack london. his brother could play the piano very well.could  his brother   play the piano very well.? his brother could not  play the piano very well. she could translate these english texts.could she  translate these english texts? .she could not translate these english texts. we must attend a lecture on german history on tuesday.must we  attend a lecture on german history on tuesday? .we must not  attend a lecture on german history on tuesday. you must return my magazines on wednesday.must you  return my magazines on wednesday? you must not  return my magazines on wednesday. you must take your children to the country for the weekend.must you  take your children to the country for the weekend? you must not  take your children to the country for the weekend. i must go to see your grandmother on my day off.must  i go to see your grandmother on my day off.? i must not  go to see your grandmother on my day off. you may discuss these questions after work.may you  discuss these questions after work.you may not  discuss these questions after work. they may take four magazines from that shelf.may they  take four magazines from that shelf.they may not take four magazines from that shelf. she may sit on the sofa in my study.may she  sit on the sofa in my study.she may not  sit on the sofa in my study. he may leave moscow on saturday.may he leave moscow on saturday? he may not leave moscow on saturday