题型:问答题 已知y=13x3+2x2+a2x+5是单调函数,则实数a的取值范围是( )A.(-∞,-1]∪[1,+∞)B.(-∞,-2]∪[2,+∞)C.(-∞,-3]∪[3,+∞)D.(-∞,-4]∪[4,+∞) 查看答案
题型:问答题 The change was so _____ that we hardly noticed it. [ ]A. actual B. actuallyC. gradual D. gradually 查看答案