如果 $\frac{x}{y}=\frac{2}{5}$，那么$\frac{y-x}{y+x}$=____

如图关于地表形态演变的叙述，与示意图相符的是（　　）

读一读，选一选

①Is he nine?____          A.  Yes, I am.

②Are you two?____         B. No, I’m four.

③Are you a boy?____        C. She is ten.

④How old is your sister？____  D. I’m a cow.

⑤Who are you?____           E. Yes, he is.