请你根据句意及所给首字母提示，补全单词。

1.We should try our best to protect the e_________.

2.There are four s_________ in a year, spring, summer, autumn and winter.

3.She is a careful girl, so she made few m_________ in the exam.

4.My brother joined the army (军队), because he wanted to be a s_________ in the future.

5.The p_________ of China is over 1.3 billion (十亿).

膜式燃气表密封性试验输入的压力为最大工作压力的（）。

A.1倍

B.1.2倍

C.1.5倍

D.1.1倍