IEnumerable<T> e = xx; foreach (var x in e) { bool a = this.A(x); if (a) { continue; } bool b = this.B(x); if (!b) { continue; } string c = ExtLibC.C(a, b) if (c == null) { continue; } DD d = ExtLibD.D(x, a, b, c) if (d == null || d.D == null || d.DD == null) { continue; }