【C4】A．spendB．requireC．settleD．retain

【C8】A．preventB．requireC．assistD．forbid

A．showB．requireC．collectD．discover

【C13】A．spendB．costC．consumeD．waste

【C15】A．spendB．investC．detectD．test

【C4】A．experiencesB．possessesC．encountersD．retains

【S4】A．spendB．useC．takeD．consume