A． essentialB． availableC． reliableD． responsible

【C2】A．essentialB．elementaryC．necessaryD．principal

A healthy diet is______for maintaining good overall health.A．essentialB．potentialC．regular

【C6】A．importantB．availableC．identicalD．necessary

【C3】A．essentialB．elementaryC．necessaryD．principal

【C6】A．agreeableB．availableC．adaptableD．approachable

He seemed to feel the（) of some explanation.A.essentialB.wishC.necessityD.necessary