الإجابة الصحيحة هي Before Alex submitted his application, he made sure he had entered all information correctly.Even though he thought he had, he was still not certain his application was complete..
الجملة الصحيحة استخدمت الفاصلة (,) بعد الجملة الابتدائية "Before Alex submitted his application". كما تم فصل الجملتين المستقلتين "he made sure he had entered all information correctly" و "Even though he thought he had he was still not certain his application was complete" بنقطة (.)، مع الحفاظ على صيغة الربط السليمة "Even though" في بداية الجملة الثانية.
