用所给动词的适当形式填空

1. Watertown is a great place for a whole family to take a vacation, for it is very_____ (interest) there.

2. Small children have _____ (organize) games and the staff dress up as clowns.

3. We will spend many happy hours _____ (walk) through the thick forests.

4. The collection of modern paintings is both _____ (fascinate) and interesting.

5. People change the way they speak when _____ (talk) with different people.

失效分析的三层含义是什么？