.Most birds find it safe to sleep in the trees, but __________ they have eggs or young chicks, they don’t use a nest.
A.why | B.how |
C.unless | D.where |
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.Most birds find it safe to sleep in the trees, but __________ they have eggs or young chicks, they don’t use a nest.
A.why | B.how |
C.unless | D.where |