When listed in order of size, which is the middle value?  $\dfrac{2}{5}      \dfrac{1}{4}      0.45      0.35      \dfrac{7}{20}$ 
Overseas Competition->Knowledge Point->Calculation Modules->Comparing, Ordering and Estimating->Comparing and Ordering->Comparing and Ordering Decimals Overseas Competition->Knowledge Point->Calculation Modules->Decimals->Basic Understanding of Decimals->Converting Fractions into Decimals