脊髓前动脉大多由下列哪支动脉发出
A. 椎动脉
B. 墓底动脉
C. 小脑后下动脉
D. 小脑上动脉
E. 大脑后动脉
Which of the following do fixed costs involve？ _____.
A. costs of officer and crew
B. loading and unloading costs
C. repair and maintenance expenses
D. administrative costs
She found it difficult to make a ____ for a single-bed room due to the conference
A. selection
B. location
C. reservation
D. conversation
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