第二节语法填空（共10小题；每小题1.5分，满分15分）
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，并将答案填写在答题卡标号为11-20的相应位置上。
To most of us, sharks are _31__ most dangerous fish in the sea, for they attack humans. However, according to Doctor Clark, ___32___ has studied the behavior of sharks for twelve years, humans are not normally on a shark’s menu. What ___33___ sharks feed on? Mainly fish and other small sea animals. Doctor Clark also found that sharks don’t eat as much food ___34___ people think. For instance, a nine-foot shark only needs two pounds of food a day to keep __35____ (health). But he says sometimes sharks starve and at other times they fill __36____ with what they have killed. Around the world, there are about 100 shark attacks on humans each year, ten of which prove fatal (致命的). But consider this: in the U.S. alone (仅仅), about 3 million people are __37____ (bite) by dogs each year. Of these, 13 people die. “If a shark bites you,” says Doctor Clark, “the reason is   38   it mistakes you as its natural food.” For example, if you went underwater fishing and saw a shark, you could be in trouble. The shark might go for the ___39___ (injure) fish you had attacked and take a big bite of you at the same time. __40____ you went into a shark’s territory (领地) and threatened it, it might try to bite you. That’s because sharks are territorial and tend to guard their territory. Like dogs, they protect the area that they think is theirs.