var collecion = new List<List<ToTest>>
{
new List<ToTest>{new ToTest {Id = 1, Name = "some name"}, new ToTest {Id = 4, Name = "some name2"}},
new List<ToTest>{new ToTest {Id = 2, Name = "some name"}, new ToTest {Id = 5, Name = "some name2"}},
new List<ToTest>{new ToTest {Id = 3, Name = "some name"}, new ToTest {Id = 6, Name = "some name2"}},
};
我想使用功能 linq 而不是 lambda linq
var result1 = collecion.SelectMany(q => q).ToList();