sharpen

See this word as a collocate cloud

mattress he must learn to	sharpen	a pencil he thinks he
can his big brother can	sharpen	a pencil but he can
simon had just begun to	sharpen	his pencil when his neighbour
that the commission needs to	sharpen	its approach to economic growth
grammar can be used to	sharpen	their awareness of the meaning
executive has done much to	sharpen	the principles of its support