It starts with zero and grows to a maximum slightly behind the wave front.

它从零值开始，并在稍后于波阵面处增长到最大值。

youdao

Successive positions of the wave front are then given by the envelopes of the secondary waves.

因此波前的相继位置即为次波的包络面。

youdao

Direction(D):the horizontal vector perpendicular to the wave front along which the crext travels.

方向（D）：运动方向，垂直于波阵面的水平方向；

youdao

He saw a man being knocked down, by the wave in front of him.

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The story talks about how FAs are trying to get in front of the wave of individual investors jettisoning brokers in favor of self-directed investing by encouraging their clients to become more involved in the investing process.

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To log into the system, players just wave their hands in front of the screen.

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