As the terrain grew craggy, Mr. Thompson kept a brisk pace, with Mr. Ortega and other officers leapfrogging ahead to help find the trail.

They say it is better to ensure the dependability and accuracy of the current machines than to leapfrog ahead to expensive, untested technology that is still evolving.

However, as China learns more about available and emerging technologies, it now has the opportunity to leapfrog ahead.

After firing a volley, they would then leapfrog ahead through fields, to another good spot and repeat the process.

He proposed leapfrogging ahead in the intermittent negotiations under way since April 1991, with both sides committing themselves to a 90-day period of nonstop talks.

AS some school districts struggle to meet higher state-mandated standards, other districts are leapfrogging ahead with programs that are more exciting - and often more rigorous.

We leapfrog ahead.

Turning in the direction of the firefight to the west, the Executioner watched as Weisskopf and Marlin leapfrogged ahead, using the rubble and the pillars for cover.

The Brotherhood infantry went in first, moving in lance formation, one five-man lance covering for another as they leapfrogged ahead in quick, sharp dashes.

But the enemy had taken concealment in doorways, up and down the west side of the main building, leapfrogging ahead for the airfield.