46. go to sea, by sea

go to sea 當(dāng)海員，出航；
by sea 乘船，由海路；by the sea 在海邊。

47. the doctor and teacher, the doctor and the teacher　

the doctor and teacher 指一個人，既是醫(yī)生又是老師；
the doctor and the teacher 兩個人，一個醫(yī)生和一個老師。

48. in office, in the office　

in office 在職的，例：He is in office, not out of office.
in the office 在辦公室里。

49. in bed, on the bed　

in bed 臥在床上，例：He is ill in bed.
on the bed 在床上，例：The book is on the bed.

50. in charge of, in the charge of　

in charge of 管理，負(fù)責(zé)照料，例：He is in charge of the matter.
in the charge of 由……照料，例：The matter is in the charge of her.