单项选择题

From the passage we know that joints and muscles perform best when __________.

A．they are twisted and stretched
B．they are in their normal positions
C．they are tested with a human "guinea pig"
D．they are tested with electronic instruments

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热门试题

单项选择题

A public scribe (Para 2. Line 1) is __________.

A．a secretary who does your business or social writing
B．a machine that does writing for you
C．a public school where writing is taught
D．a person who earns a living by writing for others

单项选择题

It can be inferred from the passage that __________.

A．a stepladder used to have four legs.
B．it is dangerous to use tools
C．a tripod is safer in a tool design
D．workers are safer on production lines