根据句子意思，用括号中所给单词的适当形式填空，并将答案填写在答题卡标号为51-56的相应位置上。
My daughter is old enough to look after         (she). She can stay at home alone.
We need to realize the         (important) of making full use of our time.
It’s so         (fair)! Mary has got more money for less work!
The students are looking forward to         (have) a holiday. They are just too busy these days.
— Jimmy will hold a party for his         (twelve) birthday. Let’s buy a present for him.
— OK. Let’s go.
It rained so         (heavy) last night that many streets were in water.