Sonar is the next step. A lot depends on technological developments to make sonar smaller -- hand-held sonar is now about the size of a lunch box.是什么意思_Sonar is the next step. A lot depends on technological developments to make sonar smaller -- hand-held sonar is now about the size of a lunch box.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句