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Deep into the sea
Human beings have sent probes into the vastness of space to explore the unknown. Meanwhile, with more than eighty percent of the world's oceans unexplored, brave explorers are trying to dive to the bottom of a really deep ocean and take a long, close look beneath the waves.
Recently, China has delivered a successful coordinated deep-sea exploration trial with the country's unmanned  submersible Haidou-1 and the manned Fendouzhe, or Striver, marking major strides from“entering”to“expediting”in the field.
With the help of Striver, Haidou-1 has become the first in the world to conduct a large-scale near-bottom topographic survey in the western depression   of the Challenger Deep during a scientific expedition to the Mariana Trench.
Tang Yuangui, chief engineer of the the vehicle, said it can flexibly respond to extreme marine conditions of all depths, and carry out scientific research activities. It is also believed that Haidou-1 has shown significant advantages in application areas including target locating, seafloor topography detection, real-time image broadcasting and  identification  of target  objects, which has provided a very effective means to support the 10,000-meter abyssal scientific research activities.
Haidou-1 has broken several world records for unmanned submersibles, including the first full-coverage acoustic cruise of the western depression of the Challenger Deep,a diving depth of 10,908 meters, and near-seabed navigation
distance of more than 14 kilometers, according to Tang.
1.What is the function of Striver?
A.To dive to the bottom of the sea.
B.To break several diving world records.
C.To help Haidou-1 conduct deep-sea survey.
D.To mark great advances in deep-sea exploration.
2.What does the underlined word“it”in the fourth paragraph refer to?
A.Haidou-1                   B.Striver
C.Mariana Trench             D.Challenger Deep
3.What is the passage mainly about?
A.Haidou-1 conducted the first topographic survey
B.Haidou-l and Striver succeeded in exploring deep space
C.China ranked first in the world in deep-sea exploration
D.China's deep-sea exploration entered a new period
1.C【解析】根据第三段“With the help of Striver, Haidou-l has become the first in the world to conduct a large-scale near-bottom topographic survey.”可知，在Striver的帮助下。海斗一号在世界上第一个进行了大规模近底地形的测量。
2.A 【解析】根据上下文可知， it指代是的海斗一号。
3.D 【解析】根据本文可知，中国通过海斗一号无人潜水器和载人奋斗者号成功地进行了深海协调勘探实验，标志着其在该领域从“进入”到“加速”迈出了重大的步伐。即中国深海勘探进入新时期。

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