The cleaners make a great contribution to _____ the city clean.
- How do you communicate_______ l your friends?-I like to chat with them_______ l the Internet.
- Who is the boy over there under the tree?- He's Li Ming,_______ leader of_____ l university football team.
---I’m sorry for my mistake at your party last night.---
We are ____ by our teacher to read English as much as possible to improve our spoken English.
We were told that we should follow the main road _we reached the bus station .