Behavior: Refers to what people say and do, with more than one measurement scale, which can be observed, described, and recorded, subject to the laws of nature, and affecting the external environment. It can be open or hidden. Based on this, Which of the following are not behaviors? ['Xiaoming writes to his parents while sitting at the computer.', 'Yuyu crying loudly while lying in the crib.', 'Little army secretly angry at the house.', 'Master Xu unscrews the plug on the oil tank.']