Grandma often tells us stories after meals, but they are quite____.

A．interesting

B．excited

C．funny

D．boring

向纯碱溶液中滴入酚酞溶液，观察到的现象是____，原因是___；若再向该溶液中滴入过量氯化钙溶液，观察到的现象是 ____，原因是___。