diff --git a/exercises/src/test/java/c1_Introduction.java b/exercises/src/test/java/c1_Introduction.java
index 92ac5493..2a8201af 100644
--- a/exercises/src/test/java/c1_Introduction.java
+++ b/exercises/src/test/java/c1_Introduction.java
@@ -1,14 +1,14 @@
-import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import java.time.Duration;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicReference;
 
-import static java.util.Collections.emptyList;
 import static org.junit.jupiter.api.Assertions.*;
 
 /**
@@ -41,7 +41,7 @@ public class c1_Introduction extends IntroductionBase {
     public void hello_world() {
         Mono<String> serviceResult = hello_world_service();
 
-        String result = null; //todo: change this line only
+        String result = serviceResult.block(); //todo: change this line only
 
         assertEquals("Hello World!", result);
     }
@@ -55,7 +55,7 @@ public void unresponsive_service() {
         Exception exception = assertThrows(IllegalStateException.class, () -> {
             Mono<String> serviceResult = unresponsiveService();
 
-            String result = null; //todo: change this line only
+            String result = serviceResult.block(Duration.ofSeconds(1)); //todo: change this line only
         });
 
         String expectedMessage = "Timeout on blocking read for 1";
@@ -72,7 +72,7 @@ public void unresponsive_service() {
     public void empty_service() {
         Mono<String> serviceResult = emptyService();
 
-        Optional<String> optionalServiceResult = null; //todo: change this line only
+        Optional<String> optionalServiceResult = serviceResult.blockOptional(); //todo: change this line only
 
         assertTrue(optionalServiceResult.isEmpty());
         assertTrue(emptyServiceIsCalled.get());
@@ -89,7 +89,7 @@ public void empty_service() {
     public void multi_result_service() {
         Flux<String> serviceResult = multiResultService();
 
-        String result = serviceResult.toString(); //todo: change this line only
+        String result = serviceResult.blockFirst(); //todo: change this line only
 
         assertEquals("valid result", result);
     }
@@ -103,7 +103,8 @@ public void multi_result_service() {
     public void fortune_top_five() {
         Flux<String> serviceResult = fortuneTop5();
 
-        List<String> results = emptyList(); //todo: change this line only
+//        List<String> results = serviceResult.take(5).toStream().toList(); //emptyList(); //todo: change this line only
+        List<String> results = serviceResult.toStream().toList(); //emptyList(); //todo: change this line only
 
         assertEquals(Arrays.asList("Walmart", "Amazon", "Apple", "CVS Health", "UnitedHealth Group"), results);
         assertTrue(fortuneTop5ServiceIsCalled.get());
@@ -126,13 +127,17 @@ public void nothing_happens_until_you_() throws InterruptedException {
 
         Flux<String> serviceResult = fortuneTop5();
 
-        serviceResult
+        var fluxHandle = serviceResult
                 .doOnNext(companyList::add)
-        //todo: add an operator here, don't use any blocking operator!
+                .subscribe() //todo: add an operator here, don't use any blocking operator!
         ;
 
+        //wait for the flux our handler 'companyList.add'
         Thread.sleep(1000); //bonus: can you explain why this line is needed?
 
+        fluxHandle.dispose();
+
+
         assertEquals(Arrays.asList("Walmart", "Amazon", "Apple", "CVS Health", "UnitedHealth Group"), companyList);
     }
 
@@ -153,6 +158,7 @@ public void leaving_blocking_world_behind() throws InterruptedException {
 
         fortuneTop5()
         //todo: change this line only
+        .subscribe(companyList::add,null, () -> serviceCallCompleted.set(true))
         ;
 
         Thread.sleep(1000);