2019-2020学年度人教版选修六 Unit 5The power of naturePeriod4Grammar课件(27张)
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Looking carefully at the ground, I made my way to the edge of the crater.

The –ing form used as an adverbial

Having experienced quite a few earthquakes in Hawaii already, I didn’t take much notice.

Having + past participle (the perfect –ing form) to refer to an action that took place before the time expressed by main verb.