1.   Selecting a location for the sculpture and memorial was as difficult as perfecting its design.

2.   The absence of explosive testing sharply increases the odds of failure and virtually rules out the possibility of perfecting new designs.

3.   China has perfected design of manned spacecraft, near launch,

4.   Elson, the flight engineer, spent the past two years trying to perfect the design of the balloon.

5.   Flight engineer Elson spent the past two years trying to perfect the design of the balloon.

6.   The official said the sports management board has not decided which option to choose, and will allow the contractor more time to perfect the design.