a first lieutenant的用法和样例：
- My father served in the Army as a first lieutenant, 117th Infantry in the 30th Division.
- He had previously spent two years at Cambridge. Now he had become a first lieutenant in a smart regiment, so he could mock at everything more becomingly in uniform.
- She got a first in maths at Exeter.
- She took a first in English at Leeds.
- She took a first class in Oxford.
- The first lieutenant faced his men about.