You might rip the straps on your mask so don't pull too hard on them.
Don't pull on your mask so hard like that, otherwise you'll tear the straps.
ーYou might rip the straps on your mask so don't pull too hard on them.
「マスクの紐がちぎれるから引っ張りすぎないで」
to rip the straps on your mask で「マスクの紐がちぎれる」
to pull too hard on ... で「…を引っ張りすぎる」
ーDon't pull on your mask so hard like that, otherwise you'll tear the straps.
そんな風にマスクを引っ張りすぎると、紐がちぎれちゃうよ」
to tear the straps で「紐がちぎれる」
ご参考まで！
カナダ 
