Many of Mr Obama's mistakes stem from a single strategic miscalculation: he is trying to do too much too quickly.

奥巴马的许多错误产生于一个简单的战略错判：他太急于求成了。

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The explanation is that each aspen while appearing to exist separately as a single tree, is in fact only the stem or shoot of a far larger organism.

对此的解释是，每一棵白杨，虽然看起来是独立存在的一棵树，但实际上只是一个巨型有机体的茎或芽。

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Single and alone in the unfathomed stillness of the soul, art thou, Lady of Silence and Solitude, a vision thrilled with light, a lonely lotus blossoming on the stem of love.

你孑身独处在灵魂的无边寂寞里，沉静而寂寞的姑娘，你是一个光芒闪耀的景象，是一朵孤独的莲花盛开在爱情的茎枝上。

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The haematopoietic stem cell transplant unit, with 10 single en-suite rooms, has been built in the hospital's former Bracken ward.

BBC: Derriford Hospital's ?3m stem cell isolation unit praised

He is working with Quake to create a thumb-size chip that can automatically catalog the genes and proteins inside a single stem cell.

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