牛津7B Unit4词组精选
1. keep +某人/某物+形容词               使某人或某物保持某种状态
  keep your eyes open                    使你的眼睛睁着
  keep your classroom clean               使你的教室干净
2. at the same time                        同时
3. walk on tiptoe                         用脚尖走路
4. as usual                               像往常一样
5. turn around                            转过身去