---What’s your favorite subject?---________, because I am interested in numbers.

 At the foot of the hill you could hear nothing but the _____ of the running water.

To be healthy, one must have at least _____ sleep every day.

Xuanwu Lake is a ______ place in Nanjing City and visitors always enjoy the ______ of it.

 I saw many ____________ eating grass on the hill.