通过提供过渡炼苗，生长素处理，适宜的介质与环境条件以及防止杂菌滋生等措施，可显著提高试管苗瓶外生根效率。
The rooting rate of test-tube plantlets could be increased obviously by seedling step-drilling, auxin treatment, suitable medium and environment conditions, control of bacterium and fungi, etc.
但在可预见的未来，亚音速飞机的形状不会发生根本的改变。
But it is unlikely that the shape of subsonic aircraft will change radically in the foreseeable future.
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