按不同形式要求用英语造句。

1.以 to do 开头 To clean the classroom is our task this afternoon.2.以 介词+doing 开头On hearing the good news ,we all jumped with joy.3.以 doing 开头Walking in the street, I met an old friend of mine.4.以 done 开头Seen from the top of the mountain ,the city looks ...