The failure of his own on the back shell, the quietly self-healing.

失败了他就缩回自己的保护壳，默默的自我疗伤。

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Four OARS, swim in water, encounter a disaster on the head. Long life, resistance to starvation, back shell can be used as medicine.

四把桨，水里游，遇到祸事就缩头。寿命长，耐饥饿，背上甲壳可入药坰——乌龟。

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While technicians took core samples of the spacecraft's heat shield around that time, in February Orion's back shell and heat shield were removed for further testing.

技术人员在大约那个时候拿到了该航天器热盾的核心样品，二月份，为了进一步测试，猎户座的背壳和热盾被移除。

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"I though it was a good response from the team, we did not just fall back into our shell and just let it all go out the window,"

VOA: standard.2009.06.07

And he gave a very good analogy in saying, "It was almost as incredible as if you'd fired a 15 inch shell at a piece of tissue paper, and it came back and hit you."

他还打过一个很好的比方：,“这就像是,你用个15英寸果壳,打到面巾纸上被弹回来打到你，一样不可思议，“

麻省理工公开课 - 化学原理课程节选

The investing class has instead pulled its collective head back into its weathered shell and mentally retreated back to the (relative) safety of looking at their own homes as a preferred investment class.

FORBES: Americans Hate Stocks

Here are three places, however, where Samsung has changed the game and will tempt Apple to shrink back into it shell.

FORBES: These Three Game Changers Define the Apple vs Samsung Battle

I'm like a little hermit crab who retreats back into his shell.

WSJ: Lingering Insecurities | John Grant | Pale Green Ghosts | By Jim Fusilli