Matching Pairs Talking About FunctionsOnline version Matching by Logos Sprachinstitut 1 The shelf is bolted to the wall with screws. 2 The bridge is supported by steel pylons. 3 The function of the switch is to turn the machine on and off. 4 The purpose of the wheel is to steer the truck. 5 The airflow is regulated by the valve. 6 The purpose of the backup file is to keep our data safe. 7 The vehicle is powered by the engine. The valve regulates the airflow. The backup file keeps our data safe. The engine powers the vehicle. Steel pylons support the bridge. Screws bolt the shelf to the wall. The switch turns the machine on and off. The wheel steers the truck.