Перекладіть речення, вкажіть стан та час присудка (active or passive) 1) the compression stroke takes place, when both valves are closed. 2) the piston must be connected to a mechanism, which controls it's sliding.

1) The compression stroke takes place(active),
      when both valves are closed (passive).
2) The piston must be connected (passive) to a mechanism,
     which controls (active) it's sliding.