Complete the following sentence with a (compound) word derived from the one(s) given in bracket. Write your word on the ANSWER SHEET.
Their efforts to improve the school have been very （ ）. (effect)
【正确答案】：EFFECTIVE
【题目解析】：
本题考查常见名词的形容词形式。
由have been和very可知，空缺处应填形容词，effect的形容词形式是effective意为“有效的”，符合题意。
句意：他们为改善学校付出的努力卓有成效。