下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。
增加：在缺词处加一个漏字符号（∧），并在其下面写上该加的词。
删除：把多余的词用斜线（\）划掉。
修改：在错的词下划一横线，并在该词下面写上修改后的词。
注意：1．每处错误及其修改均仅限一词；
2．只允许修改10处，多者（从第11处起）不计分。

例如： It was very nice to get your invitation to spend ∧ weekend with you．Luckily I was the                            am completely free then, so I’ll to  say “yes”．I’ll arrive in Bristol at around 8p．m．in Friday evening． on

Though great progress has been made in science these years, but there are still many people live
in poor conditions．They make their living by collecting and selling used thing．Their children
cannot go to school because they have not enough money to send their children to there．Why
you think so many people still suffer from poverty now?  The answer lies on the population
explosion．A president of a developing country once say: “It is us who are to blame for the
poverty because we used to ‘produce’ children without limit．” Although this few words sound
simple enough, they have clear pointed out one of the causes of the population explosion．