Câu hỏi:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.

      In 2010, the planetary defence team at NASA had identified and logged 90 per cent of the asteroids near Earth measuring 1km wide. These 'near-Earth objects', or NEOs, are the size of mountains and include anything within 50 million kilometres of Earth's orbit. With an estimated 50 left to log, NASA says none of the 887 it knows about are a significant danger to the planet. Now NASA is working towards logging (26)__________ of the smaller asteroids, those measuring 140 metres wide or more. Of the 25,000 estimated asteroids of this size, so far about 8,000 have been logged, leaving 17,000 unaccounted for. Considering that a 19-metre asteroid (27) ___________ exploded above the city of Chelyabinsk in Russia in 2013 injured 1,200 people.(28)__________, these middle-sized asteroids would be a serious danger if they enter Earth's orbit. 'Potentially Hazardous Asteroids' are rocks close enough to pass within 7.5 million kilometres of Earth's orbit. NASA has created a map of 1,400 PHAs, none of which are expected to be a threat in the next one hundred years. With technology already available, NASA can track these objects and (29)___________ predictions about possible impact, at which point two defence (30)__________ could be launched.

                                                                                                                       ( Adapted from learnenglish.org )

Now NASA is working towards logging (26)__________ of the smaller asteroids, those measuring 140 metres wide or more