己酮糖理论上具有的立体异构体数目应为()。
A.4种;
B.8种;
C.16种;
D.32种。
参考答案:B
At this time next year______ our holiday in Beijing..
A.we’re having
B.we’ll be having
C.we’ll have
D.we’re to have
汽油脱后要求硫醇含量不超过()ppm。