在一次竞赛中共有20道题，每一题答对得10分，答错或不答扣5分，小明得分要超过90分，他至少答对（ ）道题。
13
根据句意和所给的首字母填单词。
1. My mother is a nurse. She works in a famous h______.
2. Tom, if you are t______, drink this water.
3. When little Jack gets excited, he j______ up and down.
4. With the help of the local people, we found the church e______.
5. I wonder why I can't get good grades a______ I have been studying so hard.
不同铝合金可通过哪些途径达到强化目的？
