（１）I like studying English.
（２）We enjoyed talking all night.
（３）She has just finished cleaning.
（４）Chace stopped smoking last month.
（５）Playing the piano is difficult.
（６）My hobby is collecting old coins.
（７）Thank you for writing to me.
（８）I am looking forward to going to the concert.
（９）How about going to the concert?
（10）Veronica is good at playing the piano.
（11）Alec has gone to New York without saying goodbye.
（12）My father gave up smoking when I was born.