The aim of this experiment was to see if his mother was right and that cracking the knuckles causes arthritis4.

这个实验的目的就是看看他母亲是否正确，因为他母亲认为扳指关节会导致关节炎。

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The medicine prize went to a physician who, for fifty years, cracked the knuckles on only his left hand to test his mother's contention that knuckle-cracking causes arthritis.

医学奖授给了一位内科医生，他50年来每天不断扳左手手指，以验证自己母亲说扳手指会引发关节炎的话是否正确，他的结论是：妈妈，你错了。

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But because of the Academies Bill's timetable, "we have the spectacle of ministers who have already told us they will accept no amendment, period, and the sight of whips new and old cracking their knuckles off-stage and perfecting basilisk-like stares in the mirror" to prevent MPs voting for any changes, he said.

BBC: MP accuses government of intimidating backbenchers