题目内容：

Doing 做状语（即looking around ,I realized that I wa
Doing 做状语（即looking around ,I realized that I was the only passenger left on the bus这种句型）
第一部分
1 锁上门后,他回家去了.（表示时间）
2 听到这个笑话,我们大笑起来.（表示时间）
3 由于不知道下一步该做什么,所以我想问一下你的意见.(表示原因)
4 尽管他在加拿大生活了三年,他英文依然讲得不好.（表示让步）

优质解答

Locking the door,he went home.Hearing the joke,we burst into laughter.Not knowing what to do next,I would like to have your advice.Having been in Canada for three years,his English is still poor.