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【多选题】
影响寄生虫病流行的主要因素包括 :A.
气候和地理环境
B.
经济状况和医疗卫生水平
C.
相关媒介生物的存在
D.
生活习惯和生产方式
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举一反三
【单选题】I ___ my breakfast when the morning post came. A. had B. had been having C. have been having D. was having
A.
had
B.
had been having
C.
have been having
D.
was having
【简答题】在人眼的视网膜上有一个地方没有感光细胞,不能产生视觉冲动,这个地方叫( )。
【简答题】近视眼在生活中很不方便，产生近视眼的原因是眼球在______方向上太长，因此来自远处某点的光会聚在视网膜______；产生远视眼的原因是______太薄，______能力太弱，因此来自近处一点的光还没有会聚成一点就到达视网膜．
【单选题】_________to the party, Joan was greatly hurt.
A.
Having not been invited
B.
Not having been invited
C.
Having not invited
D.
Not having invited
【单选题】__________ to the party, Joan was hurt. [ ]
A.
Having not been invited
B.
Not having been invited
C.
Having not invited
D.
Not having invited
【多选题】眼晴是产生色觉和明度的要素之一 , 眼球内具有特殊的折光系统 , 通过折光系统将进入眼内的可见光汇聚在视网膜上 。 视网膜角膜上含有感光的 ( ) , 这些感光和感色细胞把接收到的色光信号传到传到大脑皮层视觉神经中枢 , 才能产生色觉和明度的感受 。
A.
视觉细胞
B.
视锥细胞
C.
视杆细胞
【多选题】4 种方法可退出 Excel
A.
单击“文件”菜单的“退出”命令。
B.
单击窗口右上角的关闭按钮。
C.
同时按下 Alt + F4 组合键。
D.
双击 Excel2010 标题栏 最左边的控制菜单按钮
【单选题】Though ______, many laws of nature exist.
A.
not having been discovered
B.
having not been discovered
C.
not having discovered
D.
having not discovered
【简答题】如果光线进入眼球经过( )后,不能在视网膜上聚焦形成清晰的( ),大脑皮层也就不能形成清晰的( ),即产生屈光不正。
【单选题】. __ many times, but he still wouldn't listen.
A.
Having told
B.
Having been told
C.
He having been told
D.
He was told
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