Eyjafjallajokull's most recent previous eruption, from late 1821 to early 1823, also had quite viscous lava. But that does not mean the volcano produced fine ash continuously.

岛山冰山最近的爆发发生于1821年年底到1823年之间，熔岩粘度也很大，但那并不意味着火山会不断地产生细火山灰。

youdao

Viscous fan drive not operating properly.

粘性风扇驱动不能正常工作。

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Liquids may not be too viscous or be susceptible to crystallization.

液体不能太粘稠，也不能易结晶。

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Tossed with crisp escarole and treviso and set off by the warm, sweet vinaigrette (which should be viscous but not heavy), the fruits complete a dish that illustrates Mr. Kahan's gift for making even the simplest of ingredients feel surprising.

WSJ: Paul Kahan's Apple Salad With Chicories, Pecans & Gorgonzola | Slow Food Fast

The primary difference between bitumen and ordinary crude is the size of the hydrocarbon molecules: in liquid oil, these molecules contain between five and twenty carbon atoms, while in bitumen they contain more than twenty. (At room temperature, pure bitumen is so viscous that it will not flow.) The main job of the upgrader is to break down the oversized hydrocarbons into smaller units.

NEWYORKER: Unconventional Crude