神经脊
A. 一条，位于神经管的腹侧
B. 一对，位于神经管的背外侧
C. 一对，位于体节外侧
D. 一条，位于脊索的腹侧
E. 一条，位于神经管的外侧
胚盘内的中胚层来源于
A. 上胚层
B. 下胚层
C. 体蒂
D. 滋养层
E. 胚外中胚层
7. The fact troubles me so much（我至今也不能通过驾驶考试）.
A. which I have been unable to pass the driving test up to now
B. because I have been unable to pass the driving test up to now
C. why I have been unable to pass the driving test up to now
D. that I have been unable to pass the driving test up to now
10. It matters little how a man dies, but what matters so much more is（他如何活着）.
A. how he lives
B. that he lives
C. why he lives
D. which he lives
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