题目

Under good treatment, Linda is beginning to _________ and will soon recover.    A. pick up                       B. turn up       C. take up                        D. show up 答案：A对于任意实数a，要使函数Y=5cox（2k+13πx-π6）（k∈N*）在区间[a，a+3]上的值54出现的次数不小于4次，又不多于8次，则k=2和32和3．