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1·Once a biological control agent is released, it is difficult to control its speed.

一旦实施了生物控制手段，它的速度就很难控制。

2·Legal consequences of attempts at biological control present a potential minefield.

尝试进行生物防治的法律后果是一个潜在的雷区。

3·How effectively biological control can be pressed into service is proved by the following examples.

下面的例子证明了生物防治如何能有效地投入使用。

4·According to law, the release of the biological control agents must be authorized by the secretary of state for the environment.

根据法律规定，发放生物控制剂必须得到环境国务秘书的批准。

5·Of course, biological control agents can safely be released only if it can be verified that they feed solely on the target weed.

当然，只有能够证明它们仅以目标杂草为食，生物控制剂才能安全释放。

6·The advantage of biological control in contrast to other methods is that it provides a relatively low-cost, perpetual control system with a minimum of detrimental side-effects.

与其他方法相比，生物防治的优点是它提供了一种成本相对较低、有害副作用最小的永久性防治系统。

7·In fact, scientists already have much of the information needed to assess the impact of biological control of bracken, but it is spread among many individuals, organizations, and government bodies.

事实上，科学家已经掌握了评估生物控制蕨类植物的影响所需要的大量信息，但是这些信息在许多个人、组织和政府机构中传播开来。

8·Biological control has been used in many parts of the world.

生物防治曾经在世界许多地方使用。

9·Research progress of the biological control for lymantria dispar l.

舞毒蛾生物防治研究进展。

10·The problems of biological control in the tea ecosystem is discussed.

讨论了茶园生物防治有待于进一步探讨的问题。