寫(xiě)英文句子時(shí)，要有明確的中心點(diǎn)，包括主語(yǔ)的人稱(chēng)、數(shù)目以及謂語(yǔ)動(dòng)詞的時(shí)態(tài)、語(yǔ)態(tài)和情態(tài)等。如果句子的中心點(diǎn)隨便改變或轉(zhuǎn)移的話，句子結(jié)構(gòu)可能陷入模糊狀態(tài)，使人困惑，也削弱了文章氣勢(shì)。
下面就是些有關(guān)句子中心點(diǎn)轉(zhuǎn)移的例子：
⒈隨便轉(zhuǎn)移主語(yǔ)和語(yǔ)態(tài)，如：
① Cocks were heard crowing as the hikers approached the farm.
在一個(gè)短短的復(fù)雜句里，原本的主句主語(yǔ)突然變成副詞從句的主語(yǔ)“the hikers”，動(dòng)詞語(yǔ)態(tài)則以被動(dòng)形式出現(xiàn)在另一個(gè)文句里。這樣的轉(zhuǎn)變沒(méi)有好處，也沒(méi)有必要。這句話可修改為：
The hikers heard cocks crowing as they approached the farm.
這里兩個(gè)主語(yǔ)保持中心點(diǎn)，一氣呵成，明確多了。
② The tourists stayed at a holiday hotel and much of their time was spent there.
這里的兩個(gè)并列句的主語(yǔ)從“the tourists”轉(zhuǎn)入“much”，動(dòng)詞則以主動(dòng)語(yǔ)態(tài)變成被動(dòng)語(yǔ)態(tài)；這樣做，必要嗎？還是改寫(xiě)一下好：
The tourists stayed at a holiday hotel and spent much of their time there.
⒉隨便轉(zhuǎn)移人稱(chēng)和數(shù)目，如：
③ Everyone will feel happy if you enjoy good life.
④ Kelvin enjoys cigarette smoking, but they make his throat sore.
在③里，人稱(chēng)“everyone”和“you”不協(xié)調(diào)所以要把“you”改成“he”或“everyone”變成“you”。如果“you”變成“he”，謂語(yǔ)動(dòng)詞“enjoy”要變成“enjoys”以便動(dòng)詞和主語(yǔ)一致：
Everyone will feel happy if he enjoys good life. You will feel happy if you enjoy good life.
在④里，用“they”指“cigarette-smoking”，不符合語(yǔ)法規(guī)則，必須把“they make”改為“it makes”人稱(chēng)和數(shù)目才配合。不這樣改也行，但“they”就要和新主語(yǔ)“cigarettes”。（不是cigarette smoking）搭擋。
⒊隨便轉(zhuǎn)移動(dòng)詞時(shí)態(tài)和情態(tài)，如：
⑤ The robber considered himself unlucky, rushed to the door, and trying to escape.
這句子中三個(gè)動(dòng)詞的時(shí)態(tài)要一致，不可以讓最后一個(gè)突然改變形式，因此“trying”要改為“tried”。
⑥ Hold your gun tightly, take aim, and you can shoot.
這里的三個(gè)短句中，兩個(gè)是祈使句，為什么最后一個(gè)突然變成陳述句？非改不可：
Hold your gun tightly, take aim and shoot.
You can hold your gun, take aim and shoot.
⑦ As I have made everything clear to him, I expected that he will let bygones be bygones.
顯然的，這里的三個(gè)動(dòng)詞的時(shí)態(tài)都可以是現(xiàn)在式，因此主句中的“expected”要改為“expect”才行。
下面就是些有關(guān)句子中心點(diǎn)轉(zhuǎn)移的例子：
⒈隨便轉(zhuǎn)移主語(yǔ)和語(yǔ)態(tài)，如：
① Cocks were heard crowing as the hikers approached the farm.
在一個(gè)短短的復(fù)雜句里，原本的主句主語(yǔ)突然變成副詞從句的主語(yǔ)“the hikers”，動(dòng)詞語(yǔ)態(tài)則以被動(dòng)形式出現(xiàn)在另一個(gè)文句里。這樣的轉(zhuǎn)變沒(méi)有好處，也沒(méi)有必要。這句話可修改為：
The hikers heard cocks crowing as they approached the farm.
這里兩個(gè)主語(yǔ)保持中心點(diǎn)，一氣呵成，明確多了。
② The tourists stayed at a holiday hotel and much of their time was spent there.
這里的兩個(gè)并列句的主語(yǔ)從“the tourists”轉(zhuǎn)入“much”，動(dòng)詞則以主動(dòng)語(yǔ)態(tài)變成被動(dòng)語(yǔ)態(tài)；這樣做，必要嗎？還是改寫(xiě)一下好：
The tourists stayed at a holiday hotel and spent much of their time there.
⒉隨便轉(zhuǎn)移人稱(chēng)和數(shù)目，如：
③ Everyone will feel happy if you enjoy good life.
④ Kelvin enjoys cigarette smoking, but they make his throat sore.
在③里，人稱(chēng)“everyone”和“you”不協(xié)調(diào)所以要把“you”改成“he”或“everyone”變成“you”。如果“you”變成“he”，謂語(yǔ)動(dòng)詞“enjoy”要變成“enjoys”以便動(dòng)詞和主語(yǔ)一致：
Everyone will feel happy if he enjoys good life. You will feel happy if you enjoy good life.
在④里，用“they”指“cigarette-smoking”，不符合語(yǔ)法規(guī)則，必須把“they make”改為“it makes”人稱(chēng)和數(shù)目才配合。不這樣改也行，但“they”就要和新主語(yǔ)“cigarettes”。（不是cigarette smoking）搭擋。
⒊隨便轉(zhuǎn)移動(dòng)詞時(shí)態(tài)和情態(tài)，如：
⑤ The robber considered himself unlucky, rushed to the door, and trying to escape.
這句子中三個(gè)動(dòng)詞的時(shí)態(tài)要一致，不可以讓最后一個(gè)突然改變形式，因此“trying”要改為“tried”。
⑥ Hold your gun tightly, take aim, and you can shoot.
這里的三個(gè)短句中，兩個(gè)是祈使句，為什么最后一個(gè)突然變成陳述句？非改不可：
Hold your gun tightly, take aim and shoot.
You can hold your gun, take aim and shoot.
⑦ As I have made everything clear to him, I expected that he will let bygones be bygones.
顯然的，這里的三個(gè)動(dòng)詞的時(shí)態(tài)都可以是現(xiàn)在式，因此主句中的“expected”要改為“expect”才行。