On February 12 the engineers successfully demonstrated the use of assault boats, pontoons, rafts, and shooting communication wire across the river with rockets and grenade launchers.是什么意思_On February 12 the engineers successfully demonstrated the use of assault boats, pontoons, rafts, and shooting communication wire across the river with rockets and grenade launchers.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句