1．The deer ____________ (low) its head to drink from the pond.
答案：lowered
2．The apples ____________(ripe) to perfection.
答案：were ripened
3．____________(irrigate) is needed to make crops grow in dry regions.
答案：Irrigation
4．The ____________(typically) family may remain one child，but some childless and only consisting of a man and a woman.
答案：typical
