从2008年起，植物学家利用电脑技术来编纂名录，这是必不可少的，因为单凭科学家双手不可能将130万植物名整理在案。
Since 2008, botanists have been using technology to help them compile the list. This was essential as scientists could not sort the 1.3million records by hand.
备份：对任何用到电脑，存储数据的人来说，备份是必不可少的。
Backups: Are essential for anybody who USES a computer and stores data.
在上一些课程的时候，用电脑教可能会更好，但是如果解释重要概念，老师仍然必不可少。
Some subjects may be better taught by using computers, but to explain important concepts a human teacher is still indispensable.
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