寫英文句子時，要有明確的中心點，包括主語的人稱、數(shù)目以及謂語動詞的時態(tài)、語態(tài)和情態(tài)等。如果句子的中心點隨便改變或轉(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。

下面就是些有關(guān)句子中心點轉(zhuǎn)移的例子：

⒈隨便轉(zhuǎn)移主語和語態(tài)，如：

① Cocks were heard crowing as the hikers approached the farm.

在一個短短的復雜句里，原本的主句主語突然變成副詞從句的主語“the hikers”，動詞語態(tài)則以被動形式出現(xiàn)在另一個文句里。這樣的轉(zhuǎn)變沒有好處，也沒有必要。這句話可修改為：

The hikers heard cocks crowing as they approached the farm.

這里兩個主語保持中心點，一氣呵成，明確多了。

② The tourists stayed at a holiday hotel and much of their time was spent there.

這里的兩個并列句的主語從“the tourists”轉(zhuǎn)入“much”，動詞則以主動語態(tài)變成被動語態(tài);這樣做，必要嗎?還是改寫一下好：

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“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”，謂語動詞“enjoy”要變成“enjoys”以便動詞和主語一致：

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”，不符合語法規(guī)則，必須把“they make”改為“it makes”人稱和數(shù)目才配合。不這樣改也行，但“they”就要和新主語“cigarettes”。(不是cigarette smoking)搭擋。

⒊隨便轉(zhuǎn)移動詞時態(tài)和情態(tài)，如：

⑤ The robber considered himself unlucky, rushed to the door, and trying to escape.

這句子中三個動詞的時態(tài)要一致，不可以讓最后一個突然改變形式，因此“trying”要改為“tried”。

⑥ Hold your gun tightly, take aim, and you can shoot.

這里的三個短句中，兩個是祈使句，為什么最后一個突然變成陳述句?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，這里的三個動詞的時態(tài)都可以是現(xiàn)在式，因此主句中的“expected”要改為“expect”才行。