The expression "speculated on" (Line 4) means______.
A. considered
B. suspected
C. expected
D. engaged in buying and selling
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John was not a very good student at school.
A. Right.
B. Wrong.
C. Doesn't Say.
Which of the following statements is true？
A. The subjects in a cross-sectional research are not of the same age group.
B. The methods of study in longitudinal research will not change over time.
C. Longitudinal research is reliable only in seeking understandings of the effects of early experiences on later development.
D. Cross-sectional methods are not usually adopted in studying, for example, the changes in intelligence over a thirty-year period.
Which of the following is NOT one of the disadvantages of a longitudinal research？
A. The subjects may become irritated at repeated testing.
B. The participants in the study may not stay in one place for many years.
C. The behavior. of a subject in the study may be measured continuously for many years.
D. Social changes may be reflected in the behaviors of the subjects participating in the study.
Some people viewed the findings with caution, noting that a cause-and-effect relationship
A. to be shown
B. to have been shown
C. to have shown
D. being shown
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