如果a2+ab=8,ab+b2=9,那么a2-b2的值是[ ]
A.-1
B.1
C.17
D.不确定
答案:A
简述综合课程的特征。
Which of the following statements is NOT true of "fractional ownership" a. "Fractional ownership" allows people share the use of highly expensive commodities. b. Thanks to "fractional ownership", people can afford luxuries like a super yacht. c. "Fractional ownership" is identical to "time sharing". d. "Fractional ownership" means part of the property right to the buyer.