Скобки, поставив глагол в нужное время. a) 1. russian machine-builders always (to use) the latest technical achievements in their work. 2. a group of engineers already (to work out) the technology for producing a new alloy. 3. most waves (to reflect) from metals.

1.Russian machine-builders always use the latest technical achievements in their work.
2.A group of engineers have already worked out the technology for producing a new alloy. 
3. Most waves reflect from metals.