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

<上一题目录下一题>

热门试题

单项选择题

What are involved in the design of a new tool according to the passage

A．Electronic instruments and a regular tool.
B．A human "guinea pig" and a regular tool.
C．Electronic instruments and a human "guinea pig".
D．Electronic instruments, a human "guinea pig" and a regular tool.

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