妈妈买桃用去7元，买苹果用去8元，一共用去多少元？[ ] A．14元 B．15元

阅读理解。

      I'm Jeff.  I'm in Beijing now.  I think Beijing Opera is very interesting.  I often go to see it. My friend Edward usually goes to see Chinese action movies on weekends.  But I stay at home and look at pictures of Beijing Opera.  I also read sad,funny or exciting stories.  I like Chinese  action movies, too.  In a word, I love China.

    根据短文内容，判断下列句子正（T）误（F）。

( )l. Jeff is in Beijing and he often goes to see Beijing Opera. 

(     )2. Jeff's friend likes Beijing Opera, too. 

(     )3. Jeff's friend usually goes to see action movies on weekends. 

( )4. Jeff usually goes to see action movies on weekends. 

(     )5. Jeff and his friend like action movies.

已知数列{a_n}的前n项和Sn=2-a_n，数列{b_n}满足b₁=1，b₃+b₇=18．且b_n+1+b_n-1=2b_n（n≥2）．

（I）数列{a_n}和{b_n}的通项公式．

（II）若b_n=a_n•c_n，求数列{c_n}的前n项和T_n．

（6分）如图所示，两根相同的轻弹簧L₁、L₂，劲度系数分别为K₁=600N/m，K₂=500N/m，悬挂重物的质量分别为m₁=2kg和m₂=4kg，若不计弹簧质量，取g=10m/s²，则平衡时弹簧L₁、L₂的伸长量分别为多少？

  简单概括资本主义生产关系的确立和发展过程。

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投资者及其一致行动人拥有权益的股份达到或者超过一个上市公司已发行股份的一定比例，应当编制详式权益变动报告书。根据规定，该一定的比例是( )。

A．达到10%，但未达到20%
B．达到5%，但未超过30%
C．达到10%，但未超过30%
D．达到20%，但未超过30%