是定語(yǔ)從句,a present是表語(yǔ),后面的空格填which,which引導(dǎo)的從句起的作用就是修飾 a present從句的類型是由從句的位置或者說(shuō)從句起的作用決定的.從句放在賓語(yǔ)的位置、起賓語(yǔ)的作用就是賓語(yǔ)從句；放在名詞/代詞之后、...為何不能理解為對(duì)賓語(yǔ)a present 進(jìn)行強(qiáng)調(diào)呢？去掉itis....that ......還是一個(gè)結(jié)構(gòu)，意思都完整的句子啊。不是嗎？如果你改成It was the present that my father bought for me yesterday.那就是強(qiáng)調(diào)句型。下面和你說(shuō)一下定語(yǔ)從句和強(qiáng)調(diào)句型的區(qū)別：◎強(qiáng)調(diào)句中的It沒(méi)有實(shí)際意義，It be與that可同時(shí)被省略；而定語(yǔ)從句中的It是主語(yǔ)，It be與that不可同時(shí)省略；◎強(qiáng)調(diào)句型中be的時(shí)態(tài)須跟后面句子的時(shí)態(tài)相一致；而定語(yǔ)從句中主句謂語(yǔ)動(dòng)詞be的時(shí)態(tài)須由主句的時(shí)間確定◎強(qiáng)調(diào)句將句子中的that不能省略，并且即使前面的名詞是事物時(shí)，也不能將that換成which；而定語(yǔ)從句中的that作賓語(yǔ)時(shí)可被省略，并且當(dāng)先行詞是事物時(shí)可用which代替?！虍?dāng)it be后面的時(shí)間、地點(diǎn)名詞作主語(yǔ)、賓語(yǔ)或表語(yǔ)時(shí)，引導(dǎo)詞可用that / which；而作其他成分時(shí)，引導(dǎo)詞須用when / which。如：(1) It is an English book (that / which) I bought yesterday. 它是我昨天買(mǎi)的書(shū)。(本句是對(duì)What is that?問(wèn)句的回答，that所引導(dǎo)的是定語(yǔ)從句，that可被省略)It was the English book that I bought yesterday. 昨天我所賣(mài)的就是這本書(shū)。(本句相當(dāng)于對(duì)I bought the English book yesterday中an English book進(jìn)行強(qiáng)調(diào))(2) It was a room where we used to have meetings. 它是我們過(guò)去常在開(kāi)會(huì)的房子。(where 所引導(dǎo)的從句對(duì)前面的room進(jìn)行說(shuō)明，它是定語(yǔ)從句)It was in the room that we used to have meetings. 過(guò)去我們開(kāi)會(huì)就在這間房子里。(in the room是被強(qiáng)調(diào)的部分，本句是強(qiáng)調(diào)句型)(3) It is a day when the people celebrate their victory. 這是人們慶祝他們的勝利的日子。(when所引導(dǎo)的從句對(duì)a day進(jìn)行說(shuō)明，是定語(yǔ)從句)It was on that day that people celebrated their victory. 就在那一天，人們慶祝了他們的勝利。(強(qiáng)調(diào)on October 1, 1949)