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hammer
hopeless swimmer; person who can't swim; someone who sinks like a stone
金づちで釘を打つ音が朝から響いている。
The sound of hammering nails has been echoing since morning.
彼は泳げないので金づちだとよくからかわれる。
He cannot swim and is often teased for sinking like a hammer.
大工が金づちを手に屋根の修理に取りかかった。
The carpenter grabbed a hammer and began repairing the roof.