Like all insects, ants have six legs. Each leg has three joints(关节). The legs of an ant are very strong so they can run very quickly. If a man could run as fast for his size as an ant can, he could run as fast as a horse. Ants can lift 20 times their own body weight.

The life of an ant is usually 45～60 days. Ants use their antennae(触角) not only(不但)for touch, but also(而且) for smell. The head of an ant has a pair of large , strong jaws(颚). The jaws open and shut sideways like a pair of scissors(剪刀). Grown-up ants cannot eat hard(硬) food. Instead they have the juice that they get from pieces of food. They throw away the dry part that is left over. An ant has two stomachs. One stomach holds the food for itself and the other is for food to be given to other ants. Like all insects, the outside of their body is hard..

Each ant group has at least one or more queens(蚁后). The job of a queen is to lay eggs and worker ants look after them.

Worker ants look after the young, protect(保护) the nest(巢) from unwanted visitors and look for food. At night worker ants move the eggs and baby ants deep into the nest to protect them from the cold. During the daytime, worker ants move the eggs and babies to the top of the nest so that they can be warmer. Each group of ants has its own smell. In this way, visitors can be made out at once. If a worker ant has found where the food is, it leaves a special smell so that the other ants in the group can find the food. Ants are clean and tidy insects. Some worker ants are given the job of taking the waste from the nest and putting it outside in a special rubbish dump(堆)!

(     ) 51. Ants can run very quickly because_______________________.

A. they have six legs              B. they are light in weight

C. their legs are strong            D. their legs have three joints

(     ) 52. The antennae of the ants are used to _____________________ .

A. touch and smell              B. move and watch   

C. get and eat food              D. open and shut sideways

(     ) 53. According to the passage, ants ________________________ .

A. eat up all the food            B. share (分享) food with others    

C. have three pairs of scissors     D. can live for three months

(     ) 54. Which sentence is right according to the passage?

A.      An ant has a long life of more than a year.  

B.      Ants can lift 2 times their own body weight.

C. There is only one queen in an ant group.   

D. Ants can tell the stranger easily by the smell.

(     ) 55. A worker ant does Not ____________________.

A. lay eggs                 B. clean their nest

C. look for food              D. look after baby ants