關(guān)于else　[金字塔]

請問，多個條件選擇時，是否需要加else，即

if.............then begin.....................end

if.............then begin.....................end

if.............then begin.....................end

還是要

if.............then begin.....................end

else if.............then begin.....................end

else if.............then begin.....................end

??

加與不加有什么區(qū)別嗎