Перед последующими сочетаниями предлоги не употребляются

Перед следующими сочетаниями предлоги не употребляются (last,this,next)-gt;gt;(week,month,year)We are students ... the morning we go ... the Institute. Our lectures begin ... 9 o'clock. We have no lectures ... Sunday. We take examinations ... January and June. We do not study ... summer. We come the classroom and sit down ... the tables. We take our books and notebooks ... the bags and put them ... the table. Our pens are ... the table too. Our bags are usually ... the tables. Sometimes they are ... the table ... the floor. During the lesson we go ... the blackboard and write sentences ... it. When the lessons are over we go the clas and go ... home. We usually come back ... the Institute ... 3 o'clock ... the aftemoon.