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the first sleep (of silkworms)
飼育している蚕が一眠に入った。
The silkworms I'm raising entered their first sleep.
一眠後の蚕は成長が早い。
Silkworms grow rapidly after their first sleep.
一眠の時期を見極めるのが難しい。
It's difficult to determine the timing of the first sleep.