托福阅读中的推理题的题干中一般含有infer, imply, most likely, least likely, probably等词，分为有共性的推理题和无共性的推理题两大类。
It should be obvious that cetaceans, whales, porpoises, and dolphins are mammals. They breathe through lungs, not through gills, and give birth to live young. Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole cannot disguise their affinities with land-dwelling mammals. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like.
Which of the following can be inferred from paragraph 1 about early sea otters?
A. It is not difficult to imagine what they looked like.
B. There were great numbers of them.
C. They lived in the sea only.
D. They did not leave many fossil remains.
Basic to any understanding of Canada in the 20 years after the Second World War is the country’s impressive population growth….
…It appeared that Canada was once more falling in step with the trend toward smaller families that had occurred all through the Western world since the time of the Industrial Revolution.
It can be inferred from the passage that before the Industrial Revolution
(A) families were larger.
(B) population statistics were unreliable.
(C) the population grew steadily.
(D) economic conditions were bad.
A folk culture is small, isolated, cohesive, conservative, nearly self-sufficient group that is homogeneous in custom and race, with a strong family or clan structure and highly developed rituals. …Unaltered folk cultures no longer exist in industrialized countries such as the United States and Canada….
By contrast, a popular culture is a large heterogeneous group, often highly individualistic and constantly changing.
What does the author imply about the United States and Canada?
(A) They value folk cultures.
(B) They have no social classes.
(C) They have popular cultures.
(D) They do not value individualism.