根据下列句子及所给汉语注释，在句子空缺处写出各单词的正确形式 。
⑴Thomas Edison ____ (发明) the light bulbs.
⑵He went into the room ____ (慢地) and sat down.
⑶You can't solve the problems____ (除非) you do it carefully.
⑷He has a kind____ (心) and often helps others.
⑸Some animals, for example, elephants and koalas, live on grass and ____ (树叶)
⑹My uncle bought me an Ipad for my ____ (第十二) birthday.
⑺So far, we've____ (成功) in saving thousands of people in danger.
中，各项都是正数，且
成等差数列，则
等于（ ）