您只能使用支持成员L2E查询，的 日期是不是那些之一。

You can only use supported members in L2E queries, and Date isn't one of those.

一个解决方法是打破你的单L2E查询到一个L2E查询后跟一个LINQ到对象查询：

One workaround is to break your single L2E query into one L2E query followed by one LINQ to Objects query:

var q = from e in Context.Entities
        select new
        {
            Id = e.Id,
            DateTime = e.DateTime
        };

var r = from e in q.AsEnumerable()
        select new
        {
            Id = e.Id,
            Date = e.DateTime.Date
        };