军军是二年级的小学生。一天,爷爷把军军叫到跟(ēn)前(qi n),说:“军军,我出道数学题,你能答出来吗?”军军很有把握(wò)地说:“加、减、乘(chéng)、除(chú)我都学过,您说吧!”爷爷说“:有一口井(jǐn),井台(tái)离(lí)水面仅(jǐn)有九尺(chǐ)深(shēn),井里有只青蛙(w Junjun is a sophomore. One day, my grandfather called the army to the front of his mouth and said, “The army, I'm in a math, can you answer it?” The military said with a certain degree of confidence: “Plus, Subtract, take (chú) I have learned, you say it! ”Grandpa said": There is a well, the well platform (tíi) from the water surface only (jǐn) ) Deep (shēn), there are only frogs (w