Hiking by oneself can be fun and good forhealth .It may also be good for _______building .

I thought it hard to complete the project at first，but I __________ my mind．

It was the last time that Liu Xiang the Olympic Games．

They were _______ busy _______ with each other to remember the time.

Maybe you could be an inventor —- maybe even good enough to ______ an idea for the next iPhone or new medicine for cancer.