1 not in the form of a liquid or gas; keeping its shape; firm 固体的; 保持形状的; 密实的 solid fuels, eg coal, wood 固体燃料（如煤、 木） solid food, ie not liquid or slightly liquid 固体食物 ..
Sincevarious load casesand every kind of stochasticinterference, thiskind of structureis fit for activecontrolmethod for the purposeofkeepingits shape.