根据句子意思，用方框内所给词的适当形式填空，每词只能用一次。

health       die       possible      develop     invent

China is a                  country.
Philip went into his room and                 (shut) the door behind him.
Noisy conditions may make people                 .
One of the greatest                  in 20th century is light.
It’s                  for him to solve the problem, because it’s too hard.