例句與造句

1. He was special assistant to the assistant secretary of the Navy for research and development from 1956 through 1959, the period when Vanguard, Polaris, and ballistic missile nuclear submarines were developed.
2. "Mount Hood " was laid down 8 May 1967 by Bethlehem Steel Corporation, Sparrows Point, Maryland; launched 17 July 1968; sponsored by Mrs . Robert A . Frosch, wife of the Assistant Secretary of the Navy for Research and Development; and was commissioned on 1 May 1971.
3. It's difficult to find assistant secretary of the navy for research and development in a sentence. 用assistant secretary of the navy for research and development造句挺難的