Playing computer games is delightful, but _______ (spend) to

題目：

Playing computer games is delightful, but _______ (spend) too much time on it may do harm.
用動詞的適當形式填空

解答：

spending
這裡有but 所以 兩個句子的動詞形式要一樣 平行原則
前半句用playing 這裡就用spending