Question

thats rated lower than the weight to be lifted, make sure the vehicle is positioned properly, as described in the vehicle service or jack/lift user manual. when jacking a vehicle, make sure the jack pad is placed under the correct lifting location as specified by the vehicle manufacturer. ensure the vehicle being lifted is not loaded. a heavily loaded vehicle could exceed the jack/lift capacity or change the vehicles center of gravity. before lifting a vehicle to full height, check the stability by gently rocking the vehicle when lifted to about knee height. keep others from standing in front or behind the vehicle when lifting. keep yourself and others from standing underneath the vehicle when lifting. dont lift a vehicle with people in it. make sure the arms of the lift are properly locked after the vehicle is lifted to about knee height. always use a supporting device (jack stand) after the vehicle is lifted. never position your body underneath a vehicle only supported by a jack. dont disable lift safety locks. always wear safety glasses and other protective equipment as required by the workplace. which of the following practices are considered unsafe, in regard to lifting or jacking a vehicle? standing underneath the vehicle while it is being lifted. using wood or concrete blocks as substitutes for jack stands. rocking the vehicle from about knee height to see if its stable on the lift. disabling lift safety devices.

Explanation:

The text clearly states that standing underneath a lifted vehicle is unsafe as it poses a risk of injury if the vehicle falls. Using wood or concrete blocks instead of proper jack - stands is also unsafe as they may not provide stable support. Disabling lift safety devices is extremely dangerous as these devices are in place to prevent accidents. Rocking the vehicle gently from knee - height to check stability is a recommended practice, not an unsafe one.

Answer:

A. Standing underneath the vehicle while it is being lifted.
B. Using wood or concrete blocks as substitutes for jack stands.
D. Disabling lift safety devices.