diff --git a/exercises/047_methods.zig b/exercises/047_methods.zig
index d2e3ee6..fad36b5 100644
--- a/exercises/047_methods.zig
+++ b/exercises/047_methods.zig
@@ -88,7 +88,7 @@ pub fn main() void {
         for (&aliens) |*alien| {
 
             // *** Zap the alien with the heat ray here! ***
-            ???.zap(???);
+            heat_ray.zap(alien);
 
             // If the alien's health is still above 0, it's still alive.
             if (alien.health > 0) aliens_alive += 1;
diff --git a/exercises/048_methods2.zig b/exercises/048_methods2.zig
index a1fbe9e..f0ce821 100644
--- a/exercises/048_methods2.zig
+++ b/exercises/048_methods2.zig
@@ -54,7 +54,7 @@ fn visitElephants(first_elephant: *Elephant) void {
 
         // This gets the next elephant or stops:
         // which method do we want here?
-        e = if (e.hasTail()) e.??? else break;
+        e = if (e.hasTail()) e.getTail() else break;
     }
 }
 
diff --git a/exercises/049_quiz6.zig b/exercises/049_quiz6.zig
index 9dbea51..2da18de 100644
--- a/exercises/049_quiz6.zig
+++ b/exercises/049_quiz6.zig
@@ -27,7 +27,13 @@ const Elephant = struct {
     // Your Elephant trunk methods go here!
     // ---------------------------------------------------
 
-    ???
+    pub fn getTrunk(self: *Elephant) *Elephant {
+        return self.trunk.?;
+    }
+
+    pub fn hasTrunk(self: *Elephant) bool {
+        return (self.trunk != null);
+    }
 
     // ---------------------------------------------------
 
diff --git a/exercises/050_no_value.zig b/exercises/050_no_value.zig
index 8c73ed3..fe78a3f 100644
--- a/exercises/050_no_value.zig
+++ b/exercises/050_no_value.zig
@@ -65,10 +65,10 @@ const std = @import("std");
 const Err = error{Cthulhu};
 
 pub fn main() void {
-    var first_line1: *const [16]u8 = ???;
+    var first_line1: *const [16]u8 = undefined;
     first_line1 = "That is not dead";
 
-    var first_line2: Err!*const [21]u8 = ???;
+    var first_line2: Err!*const [21]u8 = undefined;
     first_line2 = "which can eternal lie";
 
     // Note we need the "{!s}" format for the error union string.
@@ -77,8 +77,8 @@ pub fn main() void {
     printSecondLine();
 }
 
-fn printSecondLine() ??? {
-    var second_line2: ?*const [18]u8 = ???;
+fn printSecondLine() void {
+    var second_line2: ?*const [18]u8 = null;
     second_line2 = "even death may die";
 
     std.debug.print("And with strange aeons {s}.\n", .{second_line2.?});
diff --git a/exercises/051_values.zig b/exercises/051_values.zig
index f2653f9..848b6a8 100644
--- a/exercises/051_values.zig
+++ b/exercises/051_values.zig
@@ -87,7 +87,7 @@ pub fn main() void {
     // Let's assign the std.debug.print function to a const named
     // "print" so that we can use this new name later!
 
-    const print = ???;
+    const print = std.debug.print;
 
     // Now let's look at assigning and pointing to values in Zig.
     //
@@ -152,13 +152,13 @@ pub fn main() void {
     print("XP before:{}, ", .{glorp.experience});
 
     // Fix 1 of 2 goes here:
-    levelUp(glorp, reward_xp);
+    levelUp(&glorp, reward_xp);
 
     print("after:{}.\n", .{glorp.experience});
 }
 
 // Fix 2 of 2 goes here:
-fn levelUp(character_access: Character, xp: u32) void {
+fn levelUp(character_access: *Character, xp: u32) void {
     character_access.experience += xp;
 }
 
diff --git a/exercises/052_slices.zig b/exercises/052_slices.zig
index af5930b..0645e55 100644
--- a/exercises/052_slices.zig
+++ b/exercises/052_slices.zig
@@ -32,8 +32,8 @@ pub fn main() void {
     var cards = [8]u8{ 'A', '4', 'K', '8', '5', '2', 'Q', 'J' };
 
     // Please put the first 4 cards in hand1 and the rest in hand2.
-    const hand1: []u8 = cards[???];
-    const hand2: []u8 = cards[???];
+    const hand1: []u8 = cards[0..4];
+    const hand2: []u8 = cards[4..8];
 
     std.debug.print("Hand1: ", .{});
     printHand(hand1);
@@ -43,7 +43,7 @@ pub fn main() void {
 }
 
 // Please lend this function a hand. A u8 slice hand, that is.
-fn printHand(hand: ???) void {
+fn printHand(hand: []u8) void {
     for (hand) |h| {
         std.debug.print("{u} ", .{h});
     }
diff --git a/exercises/053_slices2.zig b/exercises/053_slices2.zig
index 545b4da..924f6a3 100644
--- a/exercises/053_slices2.zig
+++ b/exercises/053_slices2.zig
@@ -17,19 +17,19 @@ const std = @import("std");
 pub fn main() void {
     const scrambled = "great base for all your justice are belong to us";
 
-    const base1: []u8 = scrambled[15..23];
-    const base2: []u8 = scrambled[6..10];
-    const base3: []u8 = scrambled[32..];
+    const base1: []const u8 = scrambled[15..23];
+    const base2: []const u8 = scrambled[6..10];
+    const base3: []const u8 = scrambled[32..];
     printPhrase(base1, base2, base3);
 
-    const justice1: []u8 = scrambled[11..14];
-    const justice2: []u8 = scrambled[0..5];
-    const justice3: []u8 = scrambled[24..31];
+    const justice1: []const u8 = scrambled[11..14];
+    const justice2: []const u8 = scrambled[0..5];
+    const justice3: []const u8 = scrambled[24..31];
     printPhrase(justice1, justice2, justice3);
 
     std.debug.print("\n", .{});
 }
 
-fn printPhrase(part1: []u8, part2: []u8, part3: []u8) void {
+fn printPhrase(part1: []const u8, part2: []const u8, part3: []const u8) void {
     std.debug.print("'{s} {s} {s}.' ", .{ part1, part2, part3 });
 }
diff --git a/exercises/054_manypointers.zig b/exercises/054_manypointers.zig
index ede02df..63a9745 100644
--- a/exercises/054_manypointers.zig
+++ b/exercises/054_manypointers.zig
@@ -33,7 +33,7 @@ pub fn main() void {
     // we can CONVERT IT TO A SLICE. (Hint: we do know the length!)
     //
     // Please fix this line so the print statement below can print it:
-    const zen12_string: []const u8 = zen_manyptr;
+    const zen12_string: []const u8 = zen_manyptr[0..21];
 
     // Here's the moment of truth!
     std.debug.print("{s}\n", .{zen12_string});
diff --git a/exercises/055_unions.zig b/exercises/055_unions.zig
index 794f2df..a88cd2f 100644
--- a/exercises/055_unions.zig
+++ b/exercises/055_unions.zig
@@ -59,8 +59,8 @@ pub fn main() void {
     std.debug.print("Insect report! ", .{});
 
     // Oops! We've made a mistake here.
-    printInsect(ant, AntOrBee.c);
-    printInsect(bee, AntOrBee.c);
+    printInsect(ant, AntOrBee.a);
+    printInsect(bee, AntOrBee.b);
 
     std.debug.print("\n", .{});
 }
diff --git a/exercises/056_unions2.zig b/exercises/056_unions2.zig
index c46d133..bebc833 100644
--- a/exercises/056_unions2.zig
+++ b/exercises/056_unions2.zig
@@ -44,14 +44,14 @@ pub fn main() void {
     std.debug.print("Insect report! ", .{});
 
     // Could it really be as simple as just passing the union?
-    printInsect(???);
-    printInsect(???);
+    printInsect(ant);
+    printInsect(bee);
 
     std.debug.print("\n", .{});
 }
 
 fn printInsect(insect: Insect) void {
-    switch (???) {
+    switch (insect) {
         .still_alive => |a| std.debug.print("Ant alive is: {}. ", .{a}),
         .flowers_visited => |f| std.debug.print("Bee visited {} flowers. ", .{f}),
     }