Empirical studies indicate that old people

A:are less productive than younger people. B:prefer working to retiring. C:are reliable workers. D:are less dependable.

The experiences of Optimation indicate that

A:only the engineering and construction companies may have the problem of skill deficiency. B:some larger companies always take unjust measures to compete with smaller ones. C:without skillful engineers, small companies still have the ability to enlarge their scales. D:small companies are in extreme need of technical personnel with excellent skills.

Ancient Greek philosopher Aristotle viewed laughter as “a bodily exercise precious to health.” But (1) some claims to the contrary, laughing probably has little influence on physical fitness Laughter does (2) short-term changes in the function of the heart and its blood vessels, (3) heart rate and oxygen consumption But because hard laughter is difficult to (4) , a good laugh is unlikely to have (5) benefits the way, say, walking or jogging does.
(6) ，instead of straining muscles to build them, as exercise does, laughter apparently accomplishes the (7) , studies dating back to the 1930’s indicate that laughter (8) muscles, decreasing muscle tone for up to 45 minutes after the laugh dies down.
Such bodily reaction might conceivably help (9) the effects of psychological stress. Anyway, the act of laughing probably does produce other types of (10) feedback, that improve an individual’s emotional state. (11) one classical theory of emotion, our feelings are partially rooted (12) physical reactions. It was argued at the end of the 19th century that humans do not cry (13) they are sad but they become sad when the tears begin to flow.
Although sadness also (14) tears, evidence suggests that emotions can flow (15) muscular responses. In an experiment published in 1988,social psychologist Fritz Strack of the University of würzburg in Germany asked volunteers to (16) a pen either with their teeth-thereby creating an artificial smile-or with their lips, which would produce a(n) (17) expression. Those forced to exercise their enthusiastically to funny catoons than did those whose months were contracted in a frown, (19) that expressions may influence emotions rather than just the other way around (20) , the physical act of laughter could improve mood.

A:reflect B:demand C:indicate D:produce

When scientists are trying to understand a particular set of phenomena, they often make use of a "model." A model, in the scientists’ sense, is a kind of analogy or mental image of the phenomena in terms of something we are familiar with. One example is the wave model of light. We cannot see light as if it were made up of waves because experiments on light indicate that it behaves in many respects as water waves do.
The purpose of a model is to give us a mental or visual picture -- something to hold onto -- when we cannot see what is actually happening. Models often give us a deeper understanding: the analogy to a known system (for instance, water waves in the above example) can suggest new experiments to perform and can provide ideas about what other related phenomena might occur.

A:they make us think about our universe B:they were used to represent some other phenomena C:they are more precise than theories D:they indicate further direction and help us make predictions

There are some ______ (indicate) that they are generous young souls.

indications

When scientists are trying to understand a particular set of phenomena, they often make use of a "model." A model, in the scientists’ sense, is a kind of analogy or mental image of the phenomena in terms of something we are familiar with. One example is the wave model of light. We cannot see light as if it were made up of waves because experiments on light indicate that it behaves in many respects as water waves do.
The purpose of a model is to give us a mental or visual picture -- something to hold onto -- when we cannot see what is actually happening. Models often give us a deeper understanding: the analogy to a known system (for instance, water waves in the above example) can suggest new experiments to perform and can provide ideas about what other related phenomena might occur.
Models provide us with deeper understanding because ______.

A:they make us think about our universe B:they were used to represent some other phenomena C:they are more precise than theories D:they indicate further direction and help us make predictions

There are some ______ (indicate) that they are generous young souls.

indications

When scientists are trying to understand a particular set of phenomena, they often make use of a "model." A model, in the scientists’ sense, is a kind of analogy or mental image of the phenomena in terms of something we are familiar with. One example is the wave model of light. We cannot see light as if it were made up of waves because experiments on light indicate that it behaves in many respects as water waves do.
The purpose of a model is to give us a mental or visual picture -- something to hold onto -- when we cannot see what is actually happening. Models often give us a deeper understanding: the analogy to a known system (for instance, water waves in the above example) can suggest new experiments to perform and can provide ideas about what other related phenomena might occur.

A:they make us think about our universe B:they were used to represent some other phenomena C:they are more precise than theories D:they indicate further direction and help us make predictions