题目

已知，设P：函数在R上单调递减；Q：函数的定义域为R，如果“P且Q”为假命题，“P或Q”为真命题，则c的取值范围是          答案：（0 ，1/2 ]∪ [ 1 ，+∞）Kate's dad is getting old. She will go back home to see him _____it is convenient.A．becauseB．wheneverC．althoughD．Unless