The boy _____ a story, it was not true. [ ]
A. gave up
B. made up
C. ended up
答案:B
一件商品,打八折后售价是56元,降价( )元。
下列从左到右的变形,是因式分解的是( )
A.(a-1)(a+1)=a2-1
B.m2-4=(m+2)(m-2)
C.a2-b2+1=(a+b)(a-b)+1
D.2πR+2πr=2πr+2πR