Fix comments

Author: wanghaoshuang

paddle/operators/seq_expand_op.cc

@@ -27,9 +27,7 @@ class SeqExpandOp : public framework::OperatorWithKernel {
   void InferShape(framework::InferShapeContext* ctx) const override {
     PADDLE_ENFORCE(ctx->HasInput("X"));
     PADDLE_ENFORCE(ctx->HasOutput("Out"));
-    PADDLE_ENFORCE(
-        ctx->HasInput("Y"),
-        "Input(Y) of SeqExpandOp should not be null while repeat == 0.");
+    PADDLE_ENFORCE(ctx->HasInput("Y"));
     framework::DDim out_dim;
     out_dim = ctx->GetInputDim("Y");
     ctx->ShareLoD("Y", "Out");
@@ -43,14 +41,14 @@ class SeqExpandOpMaker : public framework::OpProtoAndCheckerMaker {
                    framework::OpAttrChecker* op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
     AddInput("X",
-             "(Tensor or LoDTensor) The input('X') of this operator can be a "
+             "(Tensor or LoDTensor) The input(X) of this operator can be a "
              "LoDTensor or a base Tensor.");
     AddInput("Y",
-             "(LoDTensor)The reference input('Y') of seq_expand op."
+             "(LoDTensor)The reference input(Y) of seq_expand op."
              "It must be a LoDTensor with k-level(k>0)."
-             "Input(X) will be expanded according to LOD of input(Y)."
-             "The element numbers of last level in input('Y') "
-             "must be equal to dims[0] of input('X').");
+             "The input(X) will be expanded according to LOD of input(Y)."
+             "The element numbers of last level in input(Y) "
+             "must be equal to dims[0] of input(X).");
     AddOutput("Out",
               "(LodTensor)The output of seq_expand op."
               "The lod of output will be as same as input(Y)'s lod.");
@@ -133,7 +131,7 @@ class SeqExpandOpGrad : public framework::OperatorWithKernel {
     PADDLE_ENFORCE(ctx->HasInput("X"));
     PADDLE_ENFORCE(ctx->HasInput("Out"));
     PADDLE_ENFORCE(ctx->HasInput(framework::GradVarName("Out")),
-                   "Input(Out@GRAD) should not be null");
+                   "The input(Out@GRAD) should not be null");
     auto x_dims = ctx->GetInputDim("X");
     auto x_grad_name = framework::GradVarName("X");
     if (ctx->HasOutput(x_grad_name)) {