Пожалуйста, кто знает английский! Помогите!

2. Although birds do not look like reptiles, they came from them.
Birds do not look like reptiles. However, they came from them.
3. Although Brachiosaurus was a large creature, the blue whale is even larger.
Brachiosaurus was a large creature. However, the blue whale is even larger.
4. Although scientists have learnt a lot about dinosaurs, they don't know everything.
Scientists have learnt a lot about dinosaurs. However, they don't know everything.
5. Although some ancient reptiles lived in the sea, they were not dinosaurs.
Some ancient reptiles lived in the sea. However, they were not dinosaurs.