阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空。
Have you ever heard of friendships
among animals? At a zoo in Germany, an unusual friendship developed {#blank#}1{#/blank#} a cat and a bear.
No one is quite sure how the friendship
first began. One day, some {#blank#}2{#/blank#}( worker) in the zoo noticed a black
cat was in the bear's cage（笼子 ), and the two animals were playing
together peacefully. They were surprised how well the small cat seemed to get {#blank#}3{#/blank#} with the large bear. The bear keeper allowed
the cat {#blank#}4{#/blank#}(stay) with the bear. And later the
pair and their unusual friendship{#blank#}5{#/blank#}(become) a hot topic at the zoo.
After several years, a new cage was built
for the bear. However, the cat was still in the same cage, so it walked around{#blank#}6{#/blank#}(angry) and cried to be with the bear.
The bear keeper finally took pity on{#blank#}7{#/blank#} let it stay with the bear. The cat and the
bear got{#blank#}8{#/blank#}(close) than before. They often sat
together and shared meals in{#blank#}9{#/blank#}sun.
Sometimes it may be natural for animals{#blank#}10{#/blank#}(have) their own ideas about who would
make a good friend. These may surprise humans, who usually expect animals to
form relationships with others of the same species.
