两位同学在水平路面上推动底部垫有圆木的木箱做匀速直线运动如图，其中在木箱下垫上圆木是为了__________，木箱受到推力的合力___________（填“大于、小于或等于”）它受到的摩擦力，木箱受到的合力等于_____________。

A 2-year-old client returns from surgery after a bowel resection as a result of Hirschsprung's disease. A temporary colostomy is in place. Which immediate postoperative nursing intervention takes priority ？（）

A．Changing the surgical dressing.

B．Suctioning the nasopharynx frequently to remove secretions.

C．Irrigating the colostomy with 100 ml of normal saline solution.

D．Auscultating lung sounds.