Выберите правильную форму сказуемого ( active or passive ) и переведите.

1. powerful track-laying machines ( have developed, have been developed ) for the building of railroads.

2. the road is closed because the road works ( are conducting, are being conducted ).

3. at the first railways, sleepers ( laid down, were laid down ) along the track; nowadays they ( lay down, are laid down ) transversely.​