地下にあるコンクリートの導水管（土浦市／茨城）
Schlüsselwörter
concrete,
tunnel,
indoor,
infrastructure,
construction,
improvement,
copy space,
underground,
piping,
construction,
building,
facility,
space,
work,
colossal,
steel,
unmanned,
flooding,
underground,
country,
shield,
depth,
segment,
lifeline,
aqueduct,
space
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