用作表語(yǔ)的不定式符號(hào)to可以省略嗎

當(dāng)不定式用作表語(yǔ)時(shí)，其中的to原則上不宜省略。如：

The important thing is to save lives. 救人要緊。

The problem is to find the right house. 問(wèn)題是要找到合適的房子。

His plan is to keep the affair secret. 他的計(jì)劃是將這件事保密。

The idea of the game is to hit the ball over the net. 這個(gè)游戲的意思就是要將球打過(guò)網(wǎng)去。

但有，若主語(yǔ)部分含有動(dòng)詞do（及其變化形式），則用作表語(yǔ)的不定式可以省略to。如：

The only thing to do now is (to) go on. 前進(jìn)是現(xiàn)在惟一的出路。

What I’ll do is (to) tell her the truth. 我要做的就是告訴她真相。

All I did was (to) press this button. 我所做的只是按這個(gè)電鈕。

What you have to do is (to) fill in the questionnaire. 你要做的是把問(wèn)卷填好。