While I was preparing a test paper for my students, I came across a reference where the fill in the blank read:
Although a variety of therapeutic interventions are available for this condition, none of them are specific or long-lasting, and they __________________ cause side effects, which decrease adherence to treatment.
can all/all can/all-can/can-all
Obviously, the last two are out, and I selected 'all can'. To my great surprise, the answer is 'can all'.
Enlighten me please.