I remember sometimes 　　　　 in a rush to grow up and be independent， but I was still very happy.

If ____ unsolved, the problem of food safety may lead to more serious results.

_______by beautiful green mountains and located at the foot of Lushan Mountain makes it a famous tourist attraction.

Mary is often heard ________ playing piano in the next room in the evening.

 _____ from the top of the hill, the lake is just like a mirror.