语法填空（共10小题，每小题1分，满分10分）
阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卡标号为1-１0的相应位置上。
Many Chinese students studying abroad like to stay with host families to learn their language and culture. Nowadays, many Shanghai white-collar workers have received native English-speaking 1 (national) students as their host families, too, in order to learn English from them.
It is usually free for foreign students to stay in a host family in Shanghai, but he/she must take 2 the responsibility of teaching English to at least one certain members of the family. Miss Li has always worried about her 3 (limit) English. “I never knew what to say to an English-speaking person,” said she. She has taken a number of English courses, but 4 has proved to be useful. Last year, she saw 5 advertisement recruiting（征募） host families for foreign students, and that was how Carey (from Chicago, US) came to her home. Carey is actually not a student, but a manager. She stays in Li's apartment for free, 6 has to teach Li oral English for 1 hour every day. “She could hardly speak Chinese at the beginning, and we had to guess 7 each other meant through gestures, ”said Li.
Two months later, they could talk to each other 8 gesticulating（做手势）. Now, Li can communicate with any English-speaking person freely. About one hundred Shanghai families have received foreign boarding students, and the figure 9 (rise). However, foreign boarding students can only help improve oral English, but 10 examination skills.
的CH3COOH溶液与c mol/LCH3COONa溶液等体积混合溶液显碱性
液中不断滴加氢氧化钠溶液，若c(CH3COO－) ＞c(Na+) ＞c(H+)＞ c(OH－)则δ1一定大于δ0
cmol/L的H2C2O4(草酸)溶液中，一定满足c(H2C2O4)+ c(C2O42－)=c