user: Replace all years in the following passage with the century in which it occurred

assistant: Thomas David Gordon (born in the 20th century) (also known as T. David Gordon) is a professor, media ecologist, author, pastor, and Reformed Christian theologian.

user: Identify which instrument is string or percussion: Den-den daiko, Luc huyen cam

assistant: Luc huyen cam is string, Den-den daiko is percussion.

user: Why does a boat float on water whereas some other objects sink?

assistant: Objects with less buoyant force will sink. Buoyancy is a force acting on an object that causes it to rise or move higher in the liquid. If the object is denser than the water then it sinks and if the object is less dense than the water then it floats.