Searching for people trapped under debris of a collapsed building should be done very carefully. As you clear the wreckage, you could be changing the balance of it, and further ＿＿（43）＿＿ the structure. Therefore, proper safety precautions should be taken at all times. Before starting to move large pieces of the wreckage, you should make ＿＿（44）＿＿ contact with the people trapped under it by calling out to them. You also need to make an effort to listen below the debris to catch any sign of ＿＿（45）＿＿ . Victims may respond to your call by uttering a word or tapping the debris. Even if there is no response, it ＿＿（46）＿＿ assumed that there is nobody below. The trapped person could be unconscious, or, might be too feeble to respond.