单句改错I certainly owe you a apology for not writing more often.

单句改错
阅读下列句子，修改句子中的错误，每句中有一处错误。每处错误仅涉及一个单词的增加、删除或修改。
增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。
删除：把多余的词用斜线（/）划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
注意：每处错误及其修改均仅限一词。
51. I certainly owe you a apology for not writing more often.
52. Mr Bean is an international recognised comedy character on TV and films.
53. Over time, a lot of soil has been removed, that has caused serious erosion of the land along the Yellow River.
54. I wish I was as successful with all my student as I was with Graham.
55. It was Junyan's mother taught her to be curious.
56. To avoid miss the last train, please check the time posted in the station.
57. The government has ban the use of chemical weapons.
58. Although the job takes a significant amount of time, but most students agree that the experience is worth it.
59. Each star on the flag of the United States stands of a state of the nation.
60. As time went by, I gradually adapted me to the school life.
【答案】51. a→an    
52. international→internationally    
53. that→which    
54. student→students    
55. mother后加who/that    
56. miss→misssing    
57. ban→banned    
58. 去掉but    59. of→for