Cu Chi is located at the threshold of Sai Gon and adjacent to the revolutionary base. Cu Chi played an important role in the 2 wars of resitance against the old and new colonial powers. Cu Chi was an "underground village" with its labyrinth of interlaced tunnels having a combined length of more than 200km. The main tunnel is 60-70 cm wide and 80-90 cm high. Above the tunnel is a layer of earth about 3-4 m thick, enough to sustain the weight of 50-ton tanks or heavy artillery as well as the destruction of bomb up to 100kg. Although it is an underground communication network, the tunnel is enlarged here and there into rooms large enough to hold large meetings, a medical station or art performances. Those who had set foot in that tunnel network, should greatly admire the talent, determination and endurance of the communist gue-rillas. The soil in Cu Chi, was as hard as stone, but with such rudimentary hand tools as hose and shovels, they had dug and remove tens thousand of ton of earth and stone, and camouflaged the openings so well that nobody could find them. Many people have called it a wonder of the 20th century.
1. Where is Cu Chi situated ?
a. at the entrance to Sai Gon
b. in Sai Gon 
c. in the way to a revolutionary base
d. near Cu Chi tunnels
2. Cu Chi tunnels.........
a. is very wide and long 
b. is a complicated network of winding passages
c. has a thin layer of earth above
d. connects underground networks
3. The word "them" in line 15 refer to.........
a. the guerillas
b. the tunnels
c. the openings
d. earth and stone
4. Which of the following sentences concerning Cu Chi tunnel is not mentiones
a. the tunnel is strong enough to support the destruction of bombardments
b. there are meeting places in the tunnel
c. the tunnel was dug by hand 
5. people who visited Cu Chi tunnel.........
a. set foot in that tunnel network 
b. was impressed by the work of the communist guerillas
c. admired the complication of the tunnel network
d. made it a wonder of the 20th century
6. Which of the following sentences true?
a. Cu Chi was an important revolutionary base
b. the area of Cu Chi is about 200 square km
c. the soil in Cu Chi is uncultivated
d. Cu Chi was called a wonder of 20th century