根据地理条件的不同，生态系统可以分为两大类：_______生态系统和______生态系统。

文中共有10处错误，每句中最多两处.错误涉及一个单词的增加、删除或修改。

增加：在此处加一个漏词符号（∧），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：1. 每处错误及修改均仅限一词；

2. 只允许修改10处，多者（从11处起）不计分。

Once I had to read a text-book which was so expensive for me to buy it. I couldn’t obtain it from the library and an only copy I could find was in a certain bookshop. So I will go along to the shop every afternoon and read a little of the book in a time. One day, therefore, I was disappointed to find the book missing from its usually place. He was about to leave when the owner of the shop waved at me. Expecting to be told off, I went towards him. To my surprise, the owner pointed to the book which placed in a corner. “I put it there in case it should be bought.” He said kindly, left me to continue my reading.