complete these sentences with in at or on1 The office is always very busy. . . . . the morning. 2 Our sales conference is usually. . . . . the autumn3 Max sometimes works. . . . . the weekend4 The meeting is. . . . . Friday afternoon5 Their office is closed. . . . . the afternoon 6 The fair begins. . . . 20th April7 Some shops are open . . . . . . night8 Many of our employees go on holiday. . . . July