单项选择题
A．the Apollo mission was very successful B．protection from space radiation is not an easy job C．astronauts will have deformed children or grandchildren D．radiation is not a threat to well-protected space explorers
A．Uncontrolled development. B．A warming atmosphere at a global level. C．Sunlight reaches the forest floor, dries plants and lights fires. D．No limits on logging and bad fire preventing efforts.
A．past efforts to estimate deforestation in the Amazon have completely failed B．that damages caused by logging and fires threaten the Amazon rain forest C．Amazon rainforest disappears faster than thought D．that satellite images are made use of for estimating deforestation