John was dismissed last week because of his ______ attitude towards his job.

A．informal

B．casual

C．determined

D．earnest

根据下列实验回答问题。

(1)实验A中红磷燃烧的现象为____，化学方程式为________________。待反应冷却后，打开止水夹，进入广口瓶的水不足该瓶容积的1/5，其原因可能是_____________________。

(2)实验B中检验气体b的操作是____，从该实验可以得出的结论：水是由____组成。