题目

 Wherever she is sad, her parents can always______.   A. bring her up                 B. cheer her up   C. give her up                  D. come on 答案：B19．用大小不等的三个力，同时作用在小球．以下各组力中，哪组力可使小球处于静止（　　）A．2N  3N  6NB．35N  15N  25NC．5N  15N  25ND．1N   4N   6N