下列各句中均有一处错误，找出并改正。
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。
70．She looks sadly. Could you please tell me what it is that prevents her from being as happy as before?
71．You can’t imagine how excited they were when they received these nice Spring Festival present.
72．She told me that she has been seen off by her friends at the bus stop.
73．He asked me what is the matter with me.
74．Mary’s mother asked her if he had finished her homework.
75．I want to know how many he spent on his car.
76．Do you happen to know what she address is?
77．Excuse me, and but can you tell me how I can get to the library?
78．John asked me I would like to visit his uncle’s farm with him.
79．More and more students and teachers have begun to know how importantly the foreign language is.
