EI是梁的抗弯刚度，提高它的最有效、最合理的方法是采用惯性矩大的截面形状
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In addition to working a full day at his ______ , he has to take care of his family.
A. charge
B. company
C. career
D. cash
The whole composition is good _____ some careless mistakes.
A. except for
B. except that
C. except
D. except from
Airline personnel can buy _____ tickets at reduced prices.
A. bus
B. train
C. flight
D. movie
Six _____ languages are used at the United Nations.
A. national
B. official
C. native
D. authority
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