diff --git a/dslings/en/cpp11/00-auto-and-decltype-0.cpp b/dslings/en/cpp11/00-auto-and-decltype-0.cpp
index 95b993f..10bb6fa 100644
--- a/dslings/en/cpp11/00-auto-and-decltype-0.cpp
+++ b/dslings/en/cpp11/00-auto-and-decltype-0.cpp
@@ -26,21 +26,21 @@ int main() {
     int a = 1;
     auto a1 = a; // a1's type is int
     int b = 2;
-    D2X_YOUR_ANSWER b1 = b;
+    int b1 = b;
 
     decltype(b) b2 = b; // b2's type is int
-    D2X_YOUR_ANSWER a2 = a;
+    int a2 = a;
 
     char c = 'c';
-    D2X_YOUR_ANSWER c1 = c;
-    D2X_YOUR_ANSWER c2 = c;
+    int c1 = c;
+    int c2 = c;
 
     d2x_assert_eq(a, a1);
     d2x_assert_eq(a1, a2);
     d2x_assert_eq(b, b1);
     d2x_assert_eq(b1, b2);
 
-    D2X_WAIT
+    // D2X_WAIT
 
     return 0;
 }
diff --git a/dslings/en/cpp11/00-auto-and-decltype-1.cpp b/dslings/en/cpp11/00-auto-and-decltype-1.cpp
index 1de29ba..b6c3029 100644
--- a/dslings/en/cpp11/00-auto-and-decltype-1.cpp
+++ b/dslings/en/cpp11/00-auto-and-decltype-1.cpp
@@ -26,22 +26,22 @@ int main() {
     // 1. Expressions
     int a = 1;
     auto a1 = a + 2;
-    D2X_YOUR_ANSWER a2 = a + 2 + 1.1;
+    double a2 = a + 2 + 1.1;
 
     int b = 2;
-    D2X_YOUR_ANSWER b1 = a + 0.1;
+    double b1 = a + 0.1;
     decltype(a + b + 1.1) b2 = a + b + 1.1;
 
     char c = 'c';
-    D2X_YOUR_ANSWER c1 = 1 + c;
-    D2X_YOUR_ANSWER c2 = 2 + 'a';
+    char c1 = 1 + c;
+    char c2 = 2 + 'a';
 
     d2x_assert_eq(a2, a + 2 + 1.1);
     d2x_assert_eq(b1, a + 0.1);
     d2x_assert_eq(c1, 1 + c);
     d2x_assert_eq(c2, 2 + 'a');
 
-    D2X_WAIT
+    // D2X_WAIT
 
     return 0;
 }
diff --git a/dslings/en/cpp11/00-auto-and-decltype-2.cpp b/dslings/en/cpp11/00-auto-and-decltype-2.cpp
index 7b23111..c6c962d 100644
--- a/dslings/en/cpp11/00-auto-and-decltype-2.cpp
+++ b/dslings/en/cpp11/00-auto-and-decltype-2.cpp
@@ -40,7 +40,7 @@ int main() {
     }
     std::cout << std::endl;
 
-    D2X_YOUR_ANSWER v2 = v.begin();
+    std::vector<int>::iterator v2 = v.begin();
     for (; v2 != v.end(); ++v2) {
         std::cout << *v2 << " ";
     }
@@ -48,7 +48,7 @@ int main() {
 
     auto minus_func = [](int a, int b) { return a - b; };
 
-    std::vector<std::function<D2X_YOUR_ANSWER>> funcVec = {
+    std::vector<std::function<int(int,int)>> funcVec = {
         add_func,
         minus_func
     };
@@ -56,7 +56,7 @@ int main() {
     d2x_assert_eq(funcVec[0](1, 2), 3);
     d2x_assert_eq(funcVec[1](1, 2), -1);
 
-    D2X_WAIT
+    // D2X_WAIT
 
     return 0;
 }
diff --git a/dslings/en/cpp11/00-auto-and-decltype-3.cpp b/dslings/en/cpp11/00-auto-and-decltype-3.cpp
index 6c15322..c3fd471 100644
--- a/dslings/en/cpp11/00-auto-and-decltype-3.cpp
+++ b/dslings/en/cpp11/00-auto-and-decltype-3.cpp
@@ -30,7 +30,7 @@ auto add_func(int a, double b) -> decltype(a + b) {
 }
 
 template<typename T1, typename T2>
-D2X_YOUR_ANSWER minus_func(T1 a, T2 b) -> D2X_YOUR_ANSWER {
+auto minus_func(T1 a, T2 b) -> auto {
     return a - b;
 }
 
@@ -40,7 +40,7 @@ int main() {
     d2x_assert_eq(minus_func(2, 1), 1);
     d2x_assert_eq(minus_func(1, 2.1), -1.1);
 
-    D2X_WAIT
+    // D2X_WAIT
 
     return 0;
 }
diff --git a/dslings/en/cpp11/00-auto-and-decltype-4.cpp b/dslings/en/cpp11/00-auto-and-decltype-4.cpp
index 329b6bb..0070c2b 100644
--- a/dslings/en/cpp11/00-auto-and-decltype-4.cpp
+++ b/dslings/en/cpp11/00-auto-and-decltype-4.cpp
@@ -39,22 +39,22 @@ int main() {
     // Type deduction for obj and (obj)
     type_check = std::is_same<decltype(obj), const Object>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
-    type_check = std::is_same<decltype((obj)), D2X_YOUR_ANSWER>::value;
+    type_check = std::is_same<decltype((obj)), const Object&>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
 
     // Type deduction for obj.a and (obj.a)
-    type_check = std::is_same<decltype(obj.a), D2X_YOUR_ANSWER>::value;
+    type_check = std::is_same<decltype(obj.a), const int>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
-    type_check = std::is_same<decltype((obj.a)), D2X_YOUR_ANSWER>::value;
+    type_check = std::is_same<decltype((obj.a)), const int&>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
 
     // Type deduction for obj.b and (obj.b)
-    type_check = std::is_same<decltype(obj.b), D2X_YOUR_ANSWER>::value;
+    type_check = std::is_same<decltype(obj.b), double>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
-    type_check = std::is_same<decltype((obj.b)), D2X_YOUR_ANSWER>::value;
+    type_check = std::is_same<decltype((obj.b)), const double&>::value;
     d2x_assert(type_check); type_check = false; // dont change this line
 
-    D2X_WAIT
+    // D2X_WAIT
 
     return 0;
 }
diff --git a/dslings/en/hello-mcpp.cpp b/dslings/en/hello-mcpp.cpp
index a9cb54f..fbffc03 100644
--- a/dslings/en/hello-mcpp.cpp
+++ b/dslings/en/hello-mcpp.cpp
@@ -34,17 +34,17 @@
 
 int main() {
 
-    std::cout << "hello, mcpp!" << std:endl; // 0. Fix this compilation error
+    std::cout << "hello, mcpp!" << std::endl; // 0. Fix this compilation error
 
-    int a = 1.1; // 1. Fix this runtime error, change int to double to pass the check
+    double a = 1.1; // 1. Fix this runtime error, change int to double to pass the check
 
     d2x_assert_eq(a, 1.1); // 2. Runtime checkpoint, need to fix code to pass all checkpoints (cannot directly delete checkpoint code)
 
-    D2X_YOUR_ANSWER b = a; // 3. Fix this compilation error, give b an appropriate type
+    int b = a; // 3. Fix this compilation error, give b an appropriate type
 
     d2x_assert_eq(b, 1); // 4. Runtime checkpoint 2
 
-    D2X_WAIT // 5. Delete or comment out this macro to proceed to the next exercise (project formal code practice)
+    // D2X_WAIT // 5. Delete or comment out this macro to proceed to the next exercise (project formal code practice)
 
     return 0;
 }