问题
填空题
用所给动词的适当形式填空。
1. There ______ (use) to be animals in the forests.
2. I don't think no zoos are______ (suit) for animals to live in.
3. We can see that the animals are _ (keep) in tiny cages and can hardly move at all.
4. I have never __ (see) such a big elephant like that.
5. I urge all of your readers (visit) our wonderful zoo soon.
答案
1. used
2. suitable
3. kept
4. seen
5. to visit
，q和m分别为离子的电荷量和质量）的关系式；