起初刘毅每天只能服务一两位老人，如今他一天能接七八单。真正让他开始认同这份职业，是老人们真诚的接纳。
Most of the spacecraft will burn up during reentry, but a fraction of the material making up the 1,323-pound (600-kilogram) satellite will likely reach Earth's surface without vaporizing in the atmosphere. Uncontrolled reentries of satellites with comparable mass happen quite regularly—multiple times per month, according to one recent study—but most of them are older spacecraft or spent rocket bodies.
。关于这个话题，吃瓜网提供了深入分析
Nested properties: use __ (double underscore)
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