题目

当x______________时，分式有意义． 答案：【答案】x≠－4 【解析】根据分式有意义则分母不等于0，得x+4≠0，则x≠－4.---What were you up to when she dropped in? 　 ---I _____ for a while and ______ some reading. 　 A. had played; did　　　　　　　　　　　　 B. played; did　　 C. had played; was going to do　　　　　　　 D. was playing; was going to do