Place your child on his stomach across a firm surface or your lap before taking his temperature.

使用体温计前将小孩腹部向下放在一个稳固的平面或你的大腿上。

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Now place the piston assembly on a flat, firm surface with diaphragm facing up as shown in Figure 9.

现在将活塞总成放在平整稳定的表面上，如图9所示让隔膜面朝上。

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Tiles can be fixed to any surface as long as it's flat, firm and dry.

瓷砖可以固定在任何表面上，只要这些表面是平整、坚固、干燥的。

《柯林斯英汉双解大词典》

Transfer to a firm surface and cut into slices with a pizza cutter.

CNN: Pizza Dough

This market is proving that there is a firm bid underneath the surface, but the day you start getting sloppy and giving things too much room could be the day we end up getting a more significant pullback.

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Using a similar approach, the firm wants to cover the surface of a bottle with hydrophilic (water-attracting) and hydrophobic (water-repellent) materials.

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