某料成本系料1.8，若购进单价为18元/kg的同质量的原料8kg，此料的单位成本是14.4元/kg。（）
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I had been working a couple of months ______ I had a letter from Mike.
A. when
B. until
C. that
D. while
The author doesn't think it good wearing red sweaters if ______.
A. the crowd do it
B. you can't afford them
C. you don't look good in red
D. the situation isn't safe
Football, or ______ soccer in Britain, is the most popular sport in the world.
A. called
B. it is called
C. what is called
D. something calls
--I suppose she is 30 years of age.-- ______.
A. You guess it!
B. You guessed it!
C. You are guessing it!
D. You'll guess it!
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