（）是指生产资料归公民私人所有，以雇佣劳动为基础的一种非公有制经济形式。
A.个体经济
B.私营经济
C.集体经济
D.国有经济
参考答案：B
单词拼写。
1. He always fails exams, for he spends little time making enough p ______ for his examinations.
2. Now the girl is in hospital recovering from liver f_______.
3. There were about 300 students from our school a ______the lecture yesterday.
4. He hurried here i_____ he heard the news.
5. Children are often c ______about everything. They will keep asking questions.
6. As far as I know,this scientist has made quite a few important_____(发现)in this field.
7. The company mainly_____(出版)books for children every year.
8. You should give me a clear______(解释)of your conduct.
9. Some of the students had______(体验)hardships before they entered the university.
10. He told me he was much______(羞愧)of having lied to his mother.
A、B两小球的质量分别为m和2m，图（a）所示中，A、B用轻质弹簧相连，并用细绳悬挂起来；图（b）所示中，A、B用轻质弹簧悬挂起来。在用火将细线烧断的瞬间，A、B的加速度：
A．图（a）中 aA = g aB = g
B．图（a）中 aA = 3g aB = 0
C．图（b）中 aA = 2g aB = 2g
D．图（b）中 aA = 2g aB = g
