单选题 Many animals have an excellent sense of smell, which they use in hunting. On the other hand, their eyesight may be poor. Dogs, for example, have poor eyesight and no color vision. They see only shades of gray. But the dog's sense of smell is extraordinary,
The kind of dog known as Alsatian has 220 million olfactory (嗅觉) cells. Man has five million. Scientists believe that the Alsatian is one million times better than man in finding out odors.
The human sense of smell, however, is really quite good. The average human being can distinguish more than 10,000 different odors.

单选题 According to the passage which of the following facts is NOT true?
A. Many animals have poor eyesight while their sense of smell, is quite good.
B. Dogs are color blind.
C. The human sense of smell is not good.
D. Dogs can see no more than shades of gray.

单选题 The Alsatian's olfactory cells are ______ times as many as man's.
A. forty-four B. one million
C. 220 million D. 10,000

单选题 Generally speaking, a man can tell ______ different odors.
A. five million B. more than 10,000
C. fewer than 10,000 D. no more than 10,000

单选题 The best title of the passage is "______"
A. The Human Sense of Smell
B. Dogs Have Poor Eyesight
C. Sense of Smell
D. Dogs Have Excellent Sense of Smell