题干
As long as you keep trying, your dream will certainly .
A：come in
B：come on
C：come about
D：come true
答案(点此获取答案解析）
D
As long as you keep trying, your dream will certainly .
A：come in
B：come on
C：come about
D：come true
是简易净水器示意图，净水器中的石子、细沙、纱布、棉 
花的作用是( )