∵ab有意义，
∴a≥0，b＞0．
故答案为：a≥0，b＞0．
— Did you go to the show last night?
— Yes, many a boy and many a girl in the area ______ invited. [ ]
A. were
B. has been
C. was
D. have been
对于跨国自然人从事专业性劳务取得的报酬，税收协定所规定的所得来源地确定标准有（）。
A、居住地标准
B、固定基地标准
C、国籍标准
D、停留期间标准
E、所得支付者标准
