diff --git a/src/main/po/de.po b/src/main/po/de.po
index dd9ebbd8..92331332 100644
--- a/src/main/po/de.po
+++ b/src/main/po/de.po
@@ -2854,8 +2854,8 @@ msgstr ""
 "Ist AB ∥ CD und E der Schnittpunkt von AC und BD, dann gilt EA / EC = EB / "
 "ED."
 
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Wenn AB ∥ CD und CD ⊥ EF, dann gilt AB ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Wenn AB ∥ EF und CD ⊥ AB, dann gilt CD ⊥ EF."
 
 msgid "If AB ⊥ CD, then ∠[AB,CD] = [1] (or 90 degrees)."
 msgstr "Wenn AB ⊥ CD, dann gilt ∠[AB,CD] = [1] (oder 90 Grad)."
diff --git a/src/main/po/fa.po b/src/main/po/fa.po
index 4a3c7e98..7d127519 100644
--- a/src/main/po/fa.po
+++ b/src/main/po/fa.po
@@ -2898,7 +2898,7 @@ msgid ""
 msgstr ""
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
 msgstr ""
 
 # GDD 5/1
diff --git a/src/main/po/fr.po b/src/main/po/fr.po
index ba80e354..09042b55 100644
--- a/src/main/po/fr.po
+++ b/src/main/po/fr.po
@@ -2869,8 +2869,8 @@ msgstr ""
 "Si AB ∥ CD et E est l'intersection de AC et BD, alors EA / EC = EB / ED."
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Si AB ∥ EF et CD ⊥ EF, alors CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Si AB ∥ EF et CD ⊥ AB, alors CD ⊥ EF."
 
 # GDD 5/1
 msgid "If AB ⊥ CD, then ∠[AB,CD] = [1] (or 90 degrees)."
diff --git a/src/main/po/he.po b/src/main/po/he.po
index 2360fdfd..3122d970 100644
--- a/src/main/po/he.po
+++ b/src/main/po/he.po
@@ -2846,7 +2846,7 @@ msgstr ""
 
 # GDD 4 /1
 #, fuzzy
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
 msgstr "אם AB מקביל לEF ו CD מאונך ל EF, אזי CD מאונך ל EF."
 
 # GDD 5/1
diff --git a/src/main/po/hu.po b/src/main/po/hu.po
index fc2b2cf9..09c091bf 100644
--- a/src/main/po/hu.po
+++ b/src/main/po/hu.po
@@ -2843,8 +2843,8 @@ msgid ""
 msgstr "Ha AB ∥ CD és E az AC és BD metszete, akkor EA / EC = EB / ED."
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Ha AB ∥ EF és CD ⊥ EF, akkor CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Ha AB ∥ EF és CD ⊥ AB, akkor CD ⊥ EF."
 
 # GDD 5/1
 msgid "If AB ⊥ CD, then ∠[AB,CD] = [1] (or 90 degrees)."
diff --git a/src/main/po/it.po b/src/main/po/it.po
index 97c5d27f..bf3112bf 100644
--- a/src/main/po/it.po
+++ b/src/main/po/it.po
@@ -2940,7 +2940,7 @@ msgid ""
 msgstr ""
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
 msgstr ""
 
 # GDD 5/1
diff --git a/src/main/po/keys.pot b/src/main/po/keys.pot
index 850ad45f..62988906 100644
--- a/src/main/po/keys.pot
+++ b/src/main/po/keys.pot
@@ -2804,7 +2804,7 @@ msgid "If AB ∥ CD and E is the intersection of AC and BD, then EA / EC = EB /
 msgstr ""
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
 msgstr ""
 
 # GDD 5/1
diff --git a/src/main/po/pl.po b/src/main/po/pl.po
index 750c3772..2115c8f8 100644
--- a/src/main/po/pl.po
+++ b/src/main/po/pl.po
@@ -2855,8 +2855,8 @@ msgstr ""
 
 # GDD 4 /1
 #, fuzzy
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Jeśli AB ∥ EF i CD ⊥ EF, to CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Jeśli AB ∥ EF i CD ⊥ AB, to CD ⊥ EF."
 
 # GDD 5/1
 #, fuzzy
diff --git a/src/main/po/pt.po b/src/main/po/pt.po
index bc2e3e55..67dbd783 100644
--- a/src/main/po/pt.po
+++ b/src/main/po/pt.po
@@ -2880,8 +2880,8 @@ msgid "If AB ∥ CD and E is the intersection of AC and BD, then EA / EC = EB /
 msgstr "Se AB ∥ CD e E é a interseção de AC com BD, então EA / EC = EB / ED."
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Se AB ∥ EF e CD ⊥ EF, então CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Se AB ∥ EF e CD ⊥ AB, então CD ⊥ EF."
 
 # GDD 5/1
 msgid "If AB ⊥ CD, then ∠[AB,CD] = [1] (or 90 degrees)."
diff --git a/src/main/po/rs.po b/src/main/po/rs.po
index 5fe1497b..bc325af7 100644
--- a/src/main/po/rs.po
+++ b/src/main/po/rs.po
@@ -2877,8 +2877,8 @@ msgid ""
 msgstr "Ako je AB ∥ CD i E je presek AC i BD, onda je i EA / EC = EB / ED."
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
-msgstr "Ako je AB ∥ EF i CD ⊥ EF, onda je i CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
+msgstr "Ako je AB ∥ EF i CD ⊥ AB, onda je i CD ⊥ EF."
 
 # GDD 5/1
 msgid "If AB ⊥ CD, then ∠[AB,CD] = [1] (or 90 degrees)."
diff --git a/src/main/po/zh_CN.po b/src/main/po/zh_CN.po
index bb389fac..8526476b 100644
--- a/src/main/po/zh_CN.po
+++ b/src/main/po/zh_CN.po
@@ -2935,7 +2935,7 @@ msgid ""
 msgstr ""
 
 # GDD 4 /1
-msgid "If AB ∥ EF and CD ⊥ EF, then CD ⊥ EF."
+msgid "If AB ∥ EF and CD ⊥ AB, then CD ⊥ EF."
 msgstr ""
 
 # GDD 5/1