Medicine should not be kept where it is _______ to children.

Mother is the busiest(最忙) in my_______. She always has lots of housework to do.

They welcomed the 50-year-old woman and told her that age didn’t________. She could study in the college.

Information obtained from libraries is sooner forgotten than ____

the population of the U.S.A. in 2009—It about 309 million.