多选题
1 The term moraine refers to the rock debris carried or deposited by a glacier. The term applies to the debris moved along within the glacier or on its surface, the debris left behind after the glacier melts, and the landforms made up of these debris deposits. The debris transported by a glacier is produced either by erosion of the rock beneath the glacier or by erosion on the slopes rising above the surface of the glacier. Material eroded by the glacier is carried primarily at the base of the glacier and along the outer margins of the glacier.
2 While rivers sort transported rock according to size, a glacier transports its material like a factory conveyer belt, moving the largest blocks and the finest dust next to each other at the same rate of movement over the same distance. Thus, moraine debris remains unsorted both during its transport and after it has been deposited. This unsorted glacial material is called drift. Some moraines are composed only of coarse material and large boulders, while others contain large quantities of finer-grained material such as silt and clay.
3 Once the glacial ice has retreated, the moraine deposits are left exposed on the land surface. The various landforms--moraines--indicate the position of the debris within or on the glacier during the glacier's movement. Their shape and composition also provide information about the shape, mass, and ice flow of the glacier.
2. An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
MORAINES
1 The term moraine refers to the rock debris carried or deposited by a glacier. The term applies to the debris moved along within the glacier or on its surface, the debris left behind after the glacier melts, and the landforms made up of these debris deposits. The debris transported by a glacier is produced either by erosion of the rock beneath the glacier or by erosion on the slopes rising above the surface of the glacier. Material eroded by the glacier is carried primarily at the base of the glacier and along the outer margins of the glacier.
2 While rivers sort transported rock according to size, a glacier transports its material like a factory conveyer belt, moving the largest blocks and the finest dust next to each other at the same rate of movement over the same distance. Thus, moraine debris remains unsorted both during its transport and after it has been deposited. This unsorted glacial material is called drift. Some moraines are composed only of coarse material and large boulders, while others contain large quantities of finer-grained material such as silt and clay.
3 Once the glacial ice has retreated, the moraine deposits are left exposed on the land surface. The various landforms--moraines--indicate the position of the debris within or on the glacier during the glacier's movement. Their shape and composition also provide information about the shape, mass, and ice flow of the glacier.
2. An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
【正确答案】
B、E、F
【答案解析】Key information: The debris transported by a glacier is produced either by erosion of the rock beneath the glacier or by erosion on the slopes rising above the surface of the glacier," ... moraine debris remains unsorted both during its transport and after it has been deposited...; Once the glacial ice has retreated, the moraine deposits are left exposed... The various landforms-- moraines Answer (A) is not mentioned; answers (C) and (D) are minor ideas.