[解析]
Dear Mr.Black,
I'm very thank to you for inviting me to stay with you in the coming summer vacation.I have been dreamed of seeing you again so that I can get more help from you in my English learning.And I'm afraid I cannot go to your place in this summer.I've promised my grandmother,that lives in the country,to spend this summer with him.She misses me too much that I find∧difficult to refuse her request.I'm busy prepare for my examinations at present.I planned to visit you in winter if it's convenient to you.
Best wishes,
Yours truly,
Li Ying.
详解:
81.thank改为thankful;考查形容词,这里用形容词作系动词am的表语.
82.dreamed改为dreaming;考查动词的时态,这里用现在分词构成现在完成进行时,意为"我一直梦想着…".
83.And改为But;考查连词,结合上下文分析,前面讲到"我一直梦想着再见到你",后面又说"我恐怕不能去你那里了",所以这里应该用but表示专折.
84.删掉in;考查介词,表示时间的单词summer,winter,morning,afternoon等前面有this,that等指示代词修饰时,前面不再加介词.
85.that改为who;考查关系代词,分析句子结构可知这是一个定语从句,先行词为my grandmother,故用关系代词who.
86.him改为her;考查人称代词,结合上下文分析可知,此处的人称代词指代上文的 my grandmother,故用her.
87.too改为so;考查固定搭配,这里用so与后面的that构成"so…that…"结构,意为"如此…以至于…".
88.find加it;考查固定句式,此处加上it作动词find的形式宾语,真正的宾语是后面的不定时短语.
89.prepare改为preparing;考查固定用法,be busy doing 是固定短语,意为"忙于做某事".
90.planned改为plan;考查动词的时态,本文通篇用了现在的时态,所以此处也要用一般现在时.