1 . 必要
Nnecessary必要negated conjunction 否連言
2 . 必備
Extensive use of aircraft , plastics recycling is necessarymachinery manufacturers ., 該機用途廣泛 , 是塑料再生廠家必備機械.
3 . 必需的
...hould)+v.。類似的形容詞還有:important(重要的), essential(必要的), necessary(必需的), advisable (明智的), desirable (所希望的), vital (生死攸關的
4 . 必要時
Where a duty payer considers it necessary, it may offer to file an additional declaration ., 納稅義務人認為必要時 , 也可以主動要求進行補充申報.