—Did you have _____ fun in Australia?—Sure. It was _____ unforgettable experience.
The time is drawing near _____ food raised in space will directly benefit humans below.
.Play, often seen as ______ activity for kids, is still important in ____development of teenagers.
A big step ____ to strengthen China’s health care systems since we launched an effort in 2008.
.---Let me help you cross the street.-- ______ ! I’m not that old.
We went into a hall, on _____ walls hung a few pictures of some famous scientists.