2017-2018外研版必修2M4Period3Grammar课件(38张)
2017-2018外研版必修2M4Period3Grammar课件(38张)第3页

1. 作主语

(1) -ing形式和不定式都可在句中用作主语。一般情况下可以互换。 To learn a foreign language is not easy. =Learning a foreign language is not easy. 学习外语是不容易的。