1.It's great fun walking and cycling in Guilin.
= It's great fun to walk and cycle in Guilin.
2、She went to school but didn't have breakfast this morning.
= She went to school without (having) breakfast this morning.
3、The boy was too young to dress himself.
= The boy was so young that he couldn't dress himself.
= The boy wasn't old enough to dress himself.
4、What is the length of the river?
= How long is the river?
5、Mary was traveling alone.
= Mary was traveling (all) by herself.
= Mary was traveling on her own.
注:( )表示其中内容可以省略不写.