The opposite of smooth and flat.

我知道这个肆意的反义词，就是平滑。

youdao

Contacting surfaces of the gate and body seats must be smooth and flat for effective sealing.

闸板和阀座的接触表面必须光滑、平整，才能有效地密封。

youdao

Capsule subglobose, ca. 9 mm in diam., valves slightly smooth and flat, not obviously angulate.

蒴果近球形，长约9毫米直径，裂爿稍变平静，平，不显而易见具棱。

youdao

The plastic must also be flat and smooth for the reading to be accurate, and the object must be brought to the machine (which is not very portable) for analysis, which takes yet more time.

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The mariner uses a 250 watt free-spinning motor mounted in the front wheel for propulsion and high capacity 36 volt 9 amp hour advanced lithium battery (LiFEPO4) which provide a smooth, powered ride on flat and hilly terrain.

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Over the centuries, the river had slowly carried away mountainsides, tumbling and cracking rock, reducing boulders into a rainbow of smooth, flat stones the size of a child's hand.

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