第6部分：完形填空(第51～65题，每题1分，共15分)
下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
51．A．scientists B．humans C．plants D．animals
52．A．insects B．birds C．fish D．snakes
53．A．effect B．affect C．effected D．affected
54．A．because B．for the reason that C．because of D．since
55．A．months B．days C．minutes D．weeks
56．A．flight B．fly C．movement D．transportation
57．A．prevented from B．ordered by C．helped by D．intruded on
58．A．and B．but C．therefore D．however
59．A．portions B．parts C．sections D．kinds
60．A．try B．tries C．seem D．seems
61．A．things B．parts C．cells D．actions
62．A．awaken B．woke C．awakening D．wake—up
63．A．how B．why C．where D．what
64．A．We B．It C．They D．YOU
65．A．so B．with C．such D．if