根据要求完成句子（英语）
1、我有太多的家庭作业要做.
I have ( )( )( )to do.
2、I don't know how I can do that.（改为同义句）
I don't know （ ）（ ）（ ）that.
3、尽管他很年轻,但是他会唱英文歌曲.
Though he's very young,he ( )( )( )sing English songs.