A percussion instrument consisting of a hollow cylinder or hemisphere with a membrane stretched tightly over one or both ends, played by beating with the hands or sticks.

鼓一种打击乐器，由中空的圆柱或半圆及紧绷在一端或两端的鼓膜组成，用手或棍击打演奏。

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And, as America's labour markets become ever more tightly stretched, any further fall in unemployment provides an increasingly urgent signal for a tighter monetary policy.

ECONOMIST: Monetary policy isn��t getting any easier