Where tight dredging depth tolerances are required to dredge contaminated materials the bucket-type closed-grab dredger shall incorporate a visor.是什么意思_Where tight dredging depth tolerances are required to dredge contaminated materials the bucket-type closed-grab dredger shall incorporate a visor.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句