Experiment after experiment, they tried to acquire the _____evidence and ______ data needed to solve the technical problem. [ ]

He was about to go out for a walk _____ his teacher came to visit him[ ]

About _______ of the workers in the factory were born in the _______.

While walking around the Xixi National Wetland Park, I found there were tens of thousands of people, young and old, ______ for the flower festival. Beautiful indeed!

_________ is important for us to learn Chinese well