44. a girl, one girl
a girl可泛指所有女孩, one girl指一个女孩，如：Can one girl carry such a big box?
45. take a chair, take the chair
take a chair“相当于”，sit down“坐下”，take the chair“开始开会”
46. go to sea, by sea, by the sea
go to sea“当海员、出航”，by sea“乘船、由海路”， by the sea“在海边”，如：go by sea。
47. the doctor and teacher, the doctor and the teacher
the doctor and teacher指一个人，既是医生又是老师；the doctor and the teacher指两个人，一个医生和一个老师。
48. in office, in the office
in office“在职的”，in the office“在办公室里”，如：He is in office, not out of office.
49. in bed, on the bed
in bed“卧在床上”，on the bed“在床上”，如：The book is on the bed. He is ill in bed.
50. in charge of, in the charge of
in charge of“管理、负责照料”，in the charge of“由……照料”，如：He is in charge of the matter. The matter is in the charge of her.
