为studentdb数据库的student_info表的“学号”列添加有效性约束：学号的最左边两位字符是01，正确的SQL语句是（）
A. CREATE TABLE student_info ALTER 学号 CHECK（LEFT（学号,2）=’00’）
B. ALTER TABLE student_info ALTER 学号 CHECK（LEFT（学号,2）=’01’）
C. ALTER TABLE student_info ADD CONSTRAINT 学号 CHECK（LEFT（学号,2）=’01’）
D. CREATE TABLE student_info ADD CONSTRAINT 学号 CHECK（LEFT（学号,2）=’01’）
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Her hair was a deep black, cropped short and pointing in every direction（）
A. sense of sight
B. sense of hearing
C. sense of
D. touch
E. D．sense of smell
F. E．sense of taste
The local street snacks are hot, spicy and salty（）
A. sense of taste
B. sense of hearing
C. sense of touch
D. sense of smell
E. sense of sight
_from the moon, the earth looks like a colorful ball（）
A. Seeing
B. Seen
C. Having seen
D. Having been seen
I prefer_to_（）
A. to drive; be driven
B. to drive; drive
C. driving; being driven
D. driving; driving
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