56. Nowhere in nature is aluminum found free， owing to its always_________with other lements， most commonly with oxygen.
A） combined B） having combined
C） combine D） being combined
57. His trousers are outgrown and need__________a little.
A） lengthening B） to lengthen
C） being lengthened D） to have lengthened
58._________these flowers care must be taken not to damage the roots.
A） Planting B） When you planted
C） When you plant D） Planted
59.__________the electricity should first be switched off.
A） When changing a fuse B） Changing a fuse
C） When a fuse is changed D） A fuse changed
60. It is pleasant to sit by the fire at night and hear the wind___________outside.
A） to howl B） howling C） to be howling D) howl
61. The boys next door used to like to make model aeroplane， but they seem to have stopped_________that now.
A） doing B） to do C） not doing D） not to do
62. When at last I succeeded in convincing him that I wanted to get home quickly he put his foot on the accelerator and I felt the car _________forward.
A） to leap B） to leaping C） leap D） leaping
63. Try ______ it， it isn't worth__________about.
A） forgetting ; to worry B） to forget; to worry
C） forgetting ; worrying D） to forget ; worrying
64. She found the risk_________money too GREat.
A） of losing B） to lose C） in losing D） to have lost
65.__________， he was free.
A） Having no family to provide for
B） To have no family of providing for
C） Having no family to provide
D） To have no family of providing
参考答案：
56.D对。自然界中的任何地方都找不到游离状态的铝,因为它总是与其它元素,最常见的是氧元素结合在一起。
57.A对。他已经长大,裤子需要加长一点。
58.C对。种花时要特别小心,不要伤了它的根。
59.C对。更换保险丝时,首先必须切断电源。
60.B对。晚上坐在火旁边,听着外面风号叫,是很惬意的。
61.A对。隔壁的男孩过去喜欢做飞机模型,可是他们现在似乎不再做了。
62.D对。我终于使他确信我要立即回家,他一踏加速器,我感到汽车猛然向前。
63.D对。忘记它吧,没有什么值得担忧的。
64.A对。她发觉损失钱的风险太大。
65.A对。他没家庭要供养,他完全自由。
