A:whe
B:that
C:where
D:before
密闭容器中发生如下反应:A(g)+3B(g)⇌2C(g)△H<0,根据下列速率﹣时间图象,回答下列问题:
(1)下列时刻所改变的外界条件是:t1____ ;t3____ ;t4____
(2)产物C的体积分数最大的时间段是____ ;A的物质的量最大的时间段是____
(3)反应速率最大的时间段是____
Bill is from Australia. He lives in Sydney. He can speak French and English, but he can' t speak Chinese. He has a pen pal in the United States. Her name is Lisa and she lives in New York. Bill' s favorite sport is basketball and he can play the guitar. Lisa' s favorite sport is tennis. She can't play the guitar, but she can play the piano and sing very well.
今年是国民经济和社会发展第十三个五年规划的开局之年,“十三五”规划的主要目标是确保全面建成小康社会。而在1953年开始实施的第一个五年计划中,我国集中主要力量发展的是( )