一般的,that引導(dǎo)名詞性從句時,只起連接從句的作用,本身沒有任何意義,因此在從句中不充當(dāng)任何句子成分.
　　在GMAT語法中,認(rèn)為在引導(dǎo)賓語從句時,唯一做的就是降級、連接,如果去掉功能體現(xiàn)不出來,所以堅決不能省.但在引導(dǎo)定語從句時充當(dāng)定從中的賓語時可以省,因為它那時是關(guān)系代詞,可以從從句中缺一個成分看出來降級.
　　在GMAT語法嚴(yán)格遵守連詞數(shù)=謂語動詞數(shù)-1.比如造個句子：He believed that each individual is responsible for the environmental protection of the earth.謂語動詞有believe 和is兩個,一個主句的,一個從句的,2-1=1,所以這個連詞that不能省.
　　所以嚴(yán)格來說,引導(dǎo)賓語從句的that是不可以省略的,所以如果以后想考GMAT的話,要記住這個規(guī)則哦.中國的語法專家建議綜合考慮,決定保留老外口語中的that可省這一點(diǎn),但在有一些比如agree,argue,hold,learn,observe,remark,suggest,indicate,conceive這種比較正式的書面語的謂語動詞后,就規(guī)定that不可省略;而像hear,know,grant,say,see,perceive,confess,consider,declare,understand,propose這些詞呢,口語書面都可以,that就可省可不省;但如果是think,suppose,believe,presume,dare say這種口語詞時,that通常要省略.
　　that不可省略的情況：
　　1.在主語從句、表語從句、同位語從句中(除賓語從句),that 不能省.
　　That the seas are being overfished has been known for years.(主語從句)
　　The truth is that nobody knows who invented eyeglasses.(表語從句)
　　We have to face the fact that land is fragile.(同位語從句)
　　2.在it作形式賓語的賓語從句前,that不可省.
　　They found it difficult that they would finish their work in two days.
　　3.在由and或or所連接的兩個賓語從句時,第一個從句中的that可以省;而第二個從句中的that不能省.
　　It is depressing to think (that) life is purposeless and that evolution has no higher destination.