总而言之：

就是在表达式中没有花括号。

IEnumerable<Rect> rectlist3 = rectlist.Select(rect =>newRect(rect.X + 2, rect.Y, rect.rect.Width, rect.rect.Height));   

因此=>接翻译成：

Func(Rect rect, out Rect a)

{

return rect =>newRect(rect.X + 2, rect.Y, rect.rect.Width, rect.rect.Height);

}

IEnumerable<Rect> rectlist4 = rectlist.Where(rect => rect.X>5);

Func(Rect rect, out bool a)

{

return rect => rect.X>5;

}

IEnumerable<Rect> rectlist6=rectlist4.OrderBy(rect=>rect.Y);

Func(Rect rect, out int a)

{

return rect=>rect.Y

}

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