系统能够自动地衍生出完整更新、增量更新和无效更新等需要的各种消息。
The system can automatically derive the kinds of messages needed for full update, incremental update, invalidation, etc.
您将需要把无效转发的那一行移至正确的位置，如图34所示。
You will need to move the line with the invalid forward to the correct location, shown in Figure 34.
相对无效的药物需要有效的抢救药物，而这可能掩盖了药物对于生存率的真正作用。
Relatively ineffective drugs will require effective salvage drugs, and this may obscure the true effects of a drug with regard to survival.
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