Both 用于表明動(dòng)詞意指的行為或狀態(tài),可單獨(dú)用于兩個(gè)實(shí)體中的任一個(gè).
但是,當(dāng)動(dòng)詞不能單獨(dú)用于實(shí)體中的任一個(gè)時(shí),用both 是不恰當(dāng)?shù)?在所有格結(jié)構(gòu)中,of both 通常是更確切的：the mothers of both（他們的母親） （而不是 both their mothers ）； the fault of both（他們的過(guò)錯(cuò)） （而不是 both their fault 或 both's fault ）.
當(dāng)both 與 and 在句子中用于連接平行成份時(shí),連接的詞或短語(yǔ)應(yīng)在語(yǔ)法上保持一致：in both India and China （在印度和中國(guó)）或 both in India and in China （而不是 both in India and China ）
解釋你的問(wèn)題：
1)強(qiáng)調(diào)那兩本書(shū),就應(yīng)該是both books.就是說(shuō),強(qiáng)調(diào)什么,both就在那個(gè)東西的前面.再比如：The two sisters can both drive cars是這兩位姐妹都會(huì)開(kāi)汽車(chē).如果是The two sister can drive both cars是這兩輛車(chē),她們都能開(kāi).
2)you and i are both tired 跟both you and i are tired語(yǔ)法上都可以的.
只是一個(gè)強(qiáng)調(diào)“都累”,一個(gè)強(qiáng)調(diào)“你我兩人”.
3)This book is in both Chinese and English.和This book is both in Chinese and English.
就是上面說(shuō)的當(dāng)both ...and 在句子中用于連接平行成份時(shí),連接的詞或短語(yǔ)應(yīng)在語(yǔ)法上保持一致.如果要用后者,應(yīng)該說(shuō)this book is both in Chinese and in English.