第10题: [单项选择]" We're late and the play has started." "I wonder how long ago ______." A. did it begin B. it began C. was it beginning D. it has begun 参考答案:B 答案解析:[精解] 题型：语法题。在这里关系副词短语how long ago引导的是一个宾语从句，因此从句中主谓不倒装。另外，在由“…ago”短语作状语的句子中，谓语动词一般要使用一般过去时，所以B是正确答案。
第27题: [单项选择]This is a room in Joan’s house. There is a bed, a table and some chairs in it. There’s a glass and some books on the table. Joan is in the room. Her father and mother are at the school. They all work hard.
Who is in the room A. Joan. B. Her father. C. Her mother. 参考答案:A 答案解析:[解析] 根据第四句Joan is in the room．可知琼现在在屋子里。所以应选A。
第28题: [单项选择]含有稀有碱基最多的RNA是（ ） A. mRNA B. rRNA C. tRNA D. hnRNA E. snRNA 参考答案:C
