Yunnan is       colorful     millions of people come to enjoy themselves every year.                                                                      

A．too…to

B．so…that

C．not…until

D．so…but

凡需根据水分测定结果进行校正和基准换算的分析试验，应同时测定水分．如不能同时进行，前后测定时间最多不应超过4天。