下面示意图显示了我国古代经济重心的南移经历了一个漫长的过程，与图中①相对应的时期应该是（    ）

阅读理解

These amazing animals prove that love lives on four legs.

A little girl's lifeline

Three-year-old Alida Knobloch and her 27kg golden dog, Mr. Gibbs, are almost together all the time. There is a special love between them. Alida, who suffered from serious lung (肺)disease when she was 10 months old, is unable to breathe on her own for about 45 minutes. So Mr. Gibbs has been with her everywhere, carrying 4.5kg of oxygen tanks for her. A pig that calms kids

   When Lois Brady, a famous doctor in America, visits special-needs students in San Francisco schools, she often brings along Buttercup, a black pig from Vietnam. The pig is very calm and friendly and has been trained to offer comfort to patients as well.

A Lion's big heart

   With paws the size of dinner plates, bright black eyes and a golden mane (鬃), Jupiter, a 13-year-old 250kg lion, was brought to the rescue (援救) center by Anna. In the past two years, Anna has developed a very close relationship with Jupiter.