Hi, with regard to:
“when suddenly, an enormous sawshark swam above their heads!”
Half of the answers are of the type:
“quand soudain, un requin-scie énorme est passé au-dessus de leur tête !”
This set is in a format that I’ve encountered many times.
The other half are of the type:
“lorsque soudain, un requin scie énorme leur est passé au-dessus de la tête !”
This set is outside of my grammatical experience. I’m okay with the “leur tête/la tête” difference, as I’ve learned that in French we don’t always use the possessive “leur”, and can use a definite article such as “la”, especially when the owner of the body part is obvious. But could you explain why in these “la tête” answers a “leur” has appeared in each case earlier in the sentence. Is this early “leur” necessary in order to change “leur tête” to “la tête”? How can we consider this early “leur” to connect to the later “tête” when it is separated from it so much?