✨ ベストアンサー ✨
1)
The plural of "foot" is "feet", not "feets".
→ Justin is reading a book with his feet crossed.
It's more common to say "with his legs crossed".
→ Justin is reading a book with his legs crossed.
2)
Sarah is walking with the dog following her.
Sarah is walking with the dog following behind (her).
ありがとうございます‼︎((。´・ω・)。´_ _))
とてもわかりやすかったです!