71. Her family is all music lovers. ____________ 72. Her husband is a Swiss. Her parents are both Swisses. ____________ 73. Show guests to their room. ____________ 74. This was a great surprise to me when she did a thing like that. ____________ 75. Whom are you writing ? ____________ 76. I never saw such many swans on the lake . ___________做一节圆柱形通风管所需多少铁皮,就是求通风管的________.