206 -Machhapuchhare has never been climbed because-. A) it is one of the tallest mountains in the world
B) it is regarded as sacred, and so mountaineers are not allowed to climb it
C) it is dangerously steep, which discourages mountaineers from attempting to climb it
D) it is not as challenging for climbers as the other mountains in the region
E) there aren‘t any Sherpas experienced enough to lead mountaineers to it
207 -What the passage stresses about Sherpas is that they ---- . A) are members of a religious sect trying to ban mountain -climbing in Nepal
B) climbed high mountains until the government forbade them in the 1960s
C) are essential to climbers who want to conquer the mountains in Nepal
D) don't approve of Europeans and Americans climb their mountain
E) want to be the first people to climb Machhapuchhare
Plants can summon an insect rescue team when they are attacked by pests, just as if they were calling
for a microscopic ambulance. In fact, researchers say the signal is specific enough to tell the helpful
insects exactly what to expect when they arrive on the scene. For example, two kinds of caterpillars
attack numerous crops and cost US farmers about $6 billion annually. The plants summon a black,
parasitic wasp that it is the natural enemy of the caterpillars. Scientists have known for years that
plants could send out distress calls to wasps and other insect bodyguards, but they are just beginning
to understand how sophisticated the messages can be. They hope to find out more about the signals
and eventually use them to develop chemical -free pest control systems.
208 -The passage states that ----- . A) most of the agricultural crops produced in the USA are lost to pests
B) caterpillars can help plants attacked by black wasps
C) scientists have known all about plants' distress calls for years
D) friendly insects can help plants against unfriendly ones
E) researchers have only recently become aware of the distress calls of plants
